feat: collapsible half-height panel banners with a universal gap

TitleLabel gains an optional collapsible mode: whole-banner click target,
bare +/- glyph (no pill background), per-title collapsed state persisted
in QSettings, and an expand() helper. Banners are halved to 25px with
plain text + QSS font (H3 margins would clip vertically).

- convert Zoom, Light, Omega, Smargon, Sample camera, Monochromator,
  ABR meas. pos., Beam mark, Beam center, Beam size, Dataset path and
  Loop centering to collapsible banners
- new collapsible Exp. Config. section wrapping the scan tabs
- move Manual sample from a bottom dock into the left column between
  Dataset path and Exp. Config.; Ctrl+M now expands it instead of
  raising the dock
- Beamline state banner restyled to match (25px, plain font, bare
  glyph, whole banner clickable)
- universal 11px banner gap via tighten_column() shared by both panel
  columns and the left column stack; ABR banner spans all grid columns
  and file path / manual sample drop side margins so widths align
- abort button sits under the tabs instead of pinned to the bottom
- unit tests for the collapse behavior

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/aare/gui/main_window.py

@@ -50,7 +50,6 @@ from aare.gui.panels.local_contact_panel import LocalContactDialog
 # panels
 from aare.gui.panels.log_panel import LogDock
 from aare.gui.panels.loop_centering_panel import LoopCenteringPanel
-from aare.gui.panels.manual_sample_panel import ManualSamplePanel
 from aare.gui.panels.portrait_mode import PortraitModePanel
 from aare.gui.panels.prediction_metrics_panel import PredictionMetricsPanel
 from aare.gui.panels.reference_tools_panel import ReferenceToolsPanel
@@ -86,6 +85,7 @@ from aare.gui.widgets.baton_request_dialog import BatonPendingDialog, BatonReque
 from aare.gui.widgets.busy_overlay import build_busy_overlay_style
 from aare.gui.widgets.camera_image import SampleCameraImageLabel
 from aare.gui.widgets.message_box import precondition_check
+from aare.gui.widgets.title_label import tighten_column
 from aare.gui.widgets.no_wheel_scroll_area import NoWheelScrollArea
 from aare.gui.widgets.status_bar import StatusBar
 from aare.gui.widgets.video_image import VideoGraphicsView
@@ -235,7 +235,6 @@ class MainWindow(QMainWindow):
         self.left_column = QWidget(parent=top_widget)
         self.left_column_layout = QVBoxLayout(self.left_column)
         self.left_column_layout.setContentsMargins(0, 0, 0, 0)
-        self.left_column_layout.setSpacing(8)
 
         self.data_collection = DataCollectionSettings(
             s=geom, parent=self.left_column, raster_mgr=self.raster, diffraction=diffraction
@@ -255,6 +254,8 @@ class MainWindow(QMainWindow):
         else:
             self.beamline_state_panel.hide()
         self.left_column_layout.addStretch()
+        # Same universal banner gap as inside the panel columns.
+        tighten_column(self.left_column_layout)
 
         top_widget_layout.addWidget(self.collection_controls_scroll)
         self.collection_controls_scroll.setWidget(self.left_column)
@@ -356,6 +357,9 @@ class MainWindow(QMainWindow):
         )
         top_widget_layout.addWidget(self.beamline_controls_scroll)
         self.beamline_controls_scroll.setWidget(self.beamline)
+        # Resizable so the column shrinks when panels collapse; without it the
+        # scrollbar keeps dead range below the collapsed panels.
+        self.beamline_controls_scroll.setWidgetResizable(True)
         self.beamline_controls_scroll.setHorizontalScrollBarPolicy(
             Qt.ScrollBarPolicy.ScrollBarAlwaysOff
         )
@@ -400,13 +404,10 @@ class MainWindow(QMainWindow):
         self.job_list_dock.setAllowedAreas(Qt.DockWidgetArea.BottomDockWidgetArea)
         self.addDockWidget(Qt.DockWidgetArea.BottomDockWidgetArea, self.job_list_dock)
 
-        self.manual_sample_panel = ManualSamplePanel()
-
-        self.manual_sample_dock = QDockWidget("Manual sample", self)
-        self.manual_sample_dock.setObjectName("manual_sample_dock")
-        self.manual_sample_dock.setWidget(self.manual_sample_panel)
-        self.manual_sample_dock.setAllowedAreas(Qt.DockWidgetArea.BottomDockWidgetArea)
-        self.addDockWidget(Qt.DockWidgetArea.BottomDockWidgetArea, self.manual_sample_dock)
+        # Manual sample lives in the left column (DataCollectionSettings)
+        # between Dataset path and Exp. Config., collapsible like its
+        # neighbors — it is no longer a bottom dock.
+        self.manual_sample_panel = self.data_collection.manual_sample_panel
 
         self.automation_progress_panel = AutomationProgressWidget()
         self.automation_progress_dock = QDockWidget("Automation progress", self)
@@ -446,9 +447,6 @@ class MainWindow(QMainWindow):
 
         self.tabifyDockWidget(self.automation_progress_dock, self.log_dock)
 
-        self.tabifyDockWidget(self.manual_sample_dock, self.automation_progress_dock)
-        self.tabifyDockWidget(self.automation_progress_dock, self.log_dock)
-
         self.job_list_panel.samples_in_queue_changed.connect(
             self.automation_progress_panel.set_samples_in_queue
         )
@@ -888,10 +886,10 @@ class MainWindow(QMainWindow):
         register_tutorials(self, self.tutorial_manager)
 
     def _setup_global_shortcuts(self) -> None:
-        self._shortcut_manual_sample = QAction("Raise Manual Sample Dock", self)
+        self._shortcut_manual_sample = QAction("Expand Manual Sample", self)
         self._shortcut_manual_sample.setShortcut(QKeySequence("Ctrl+M"))
         self._shortcut_manual_sample.triggered.connect(
-            lambda: (self.manual_sample_dock.setVisible(True), self.manual_sample_dock.raise_())
+            lambda: self.manual_sample_panel.title.expand()
         )
         self.addAction(self._shortcut_manual_sample)
 
@@ -1114,7 +1112,6 @@ class MainWindow(QMainWindow):
 
         self.tell_samples_dock.setVisible(False)
         self.job_list_dock.setVisible(False)
-        self.manual_sample_dock.setVisible(False)
         self.automation_progress_dock.setVisible(False)
         self.face_panel_dock.setVisible(False)
         self.fluor_panel_dock.setVisible(False)
@@ -1192,7 +1189,6 @@ class MainWindow(QMainWindow):
         for dock_attr in (
             "tell_samples_dock",
             "job_list_dock",
-            "manual_sample_dock",
             "automation_progress_dock",
             "face_panel_dock",
             "fluor_panel_dock",
@@ -1260,7 +1256,6 @@ class MainWindow(QMainWindow):
 
         self.tell_samples_dock.setVisible(True)
         self.job_list_dock.setVisible(True)
-        self.manual_sample_dock.setVisible(True)
         self.automation_progress_dock.setVisible(False)
         self.face_panel_dock.setVisible(False)
         self.fluor_panel_dock.setVisible(False)
@@ -1462,15 +1457,6 @@ class MainWindow(QMainWindow):
         self.job_list_dock.visibilityChanged.connect(show_job_list_action.setChecked)
         view_menu.addAction(show_job_list_action)
 
-        show_manual_sample_action = QAction("Show manual sample", self)
-        show_manual_sample_action.setCheckable(True)
-        show_manual_sample_action.setChecked(True)
-        show_manual_sample_action.triggered.connect(
-            lambda checked: self.manual_sample_dock.setVisible(checked)
-        )
-        self.manual_sample_dock.visibilityChanged.connect(show_manual_sample_action.setChecked)
-        view_menu.addAction(show_manual_sample_action)
-
         show_face_panel_action = QAction("Show face detection", self)
         show_face_panel_action.setCheckable(True)
         show_face_panel_action.setChecked(False)
@@ -1611,7 +1597,6 @@ class MainWindow(QMainWindow):
 
         self.tell_samples_dock.setVisible(True)
         self.job_list_dock.setVisible(True)
-        self.manual_sample_dock.setVisible(True)
 
         if self._beamline_state_panel_enabled:
             self.beamline_state_panel.setVisible(True)

src/aare/gui/panels/abr_tweak_panel.py

@@ -95,7 +95,9 @@ class AbrTweakWidget(QWidget):
         grid_layout.setColumnStretch(1, 0)
         grid_layout.setColumnStretch(2, 1)
 
-        grid_layout.addWidget(TitleLabel("ABR meas. pos.", self), 0, 0, 1, 3)
+        # Span all 4 grid columns (the ABR buttons row uses 4), otherwise the
+        # banner renders narrower than the neighboring panels.
+        grid_layout.addWidget(TitleLabel("ABR meas. pos.", self, collapsible=True), 0, 0, 1, 4)
 
         self._abr_buttons = AbrTweakButtons(DEFAULT_ABR_STEP_UM / 1000, parent=self)
         grid_layout.addWidget(self._abr_buttons, 1, 0, 1, 4)

src/aare/gui/panels/beam_center_panel.py

@@ -14,7 +14,7 @@ class BeamCenterWidget(QWidget):
 
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Beam center (detector)", self), 0, 0, 1, 5)
+        grid_layout.addWidget(TitleLabel("Beam center (detector)", self, collapsible=True), 0, 0, 1, 5)
 
         self.x = NumberLineEdit(-4000, 4000, 0, parent=self)
         self.x.newValue.connect(self.beam_center_edited)

src/aare/gui/panels/beam_mark_panel.py

@@ -13,7 +13,7 @@ class BeamMarkWidget(QWidget):
 
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Beam mark (image)", self), 0, 0, 1, 5)
+        grid_layout.addWidget(TitleLabel("Beam mark (image)", self, collapsible=True), 0, 0, 1, 5)
 
         self.x = QLabel("0")
         self.y = QLabel("0")

src/aare/gui/panels/beam_size_panel.py

@@ -14,7 +14,7 @@ class BeamSizeWidget(QWidget):
 
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Beam size", self), 0, 0, 1, 5)
+        grid_layout.addWidget(TitleLabel("Beam size", self, collapsible=True), 0, 0, 1, 5)
 
         self.x = NumberLineEdit(1, 400.0, 10, parent=self)
         self.x.newValue.connect(self.beam_size_edited)

src/aare/gui/panels/beamline_controls.py

@@ -10,6 +10,7 @@ from aare.gui.panels.omega_panel import OmegaPanel
 from aare.gui.panels.samcam_panel import SamcamPanel
 from aare.gui.panels.smargon_panel import SmargonPanel
 from aare.gui.panels.zoom_panel import ZoomPanel
+from aare.gui.widgets.title_label import tighten_column
 
 
 class BeamlineControls(QFrame):
@@ -51,4 +52,5 @@ class BeamlineControls(QFrame):
             self.v_layout.addWidget(self.beam_size)
 
         self.v_layout.addStretch()
+        tighten_column(self.v_layout)
         self.setLayout(self.v_layout)

src/aare/gui/panels/beamline_state_panel.py

@@ -6,6 +6,8 @@ from PySide6.QtCore import QPoint, QRect, Qt, Signal, Slot
 from PySide6.QtGui import QColor, QPainter, QPen
 from PySide6.QtWidgets import QFrame, QLabel, QPushButton
 
+from aare.gui.widgets.title_label import PANEL_VMARGIN
+
 
 @dataclass(frozen=True)
 class StationSpec:
@@ -57,8 +59,11 @@ class BeamlineStatePanel(QFrame):
 
     set_width = 400
     map_height = 542
-    title_height = 50
-    collapsed_height = 50
+    # 25 matches the halved TitleLabel banners used by every other panel;
+    # PANEL_VMARGIN mimics the layout margin other panels get from
+    # tighten_column, so the inter-banner gap stays universal.
+    title_height = 25
+    collapsed_height = title_height + 2 * PANEL_VMARGIN
     station_radius = 8
 
     def __init__(self, parent=None):
@@ -209,16 +214,22 @@ class BeamlineStatePanel(QFrame):
 
         self.title = QLabel(self)
         self.title.setObjectName("beamlineStateTitle")
-        self.title.setText("<H3>Beamline state</H3>")
+        # Plain text + QSS font: <H3> margins would clip in the 25px banner.
+        self.title.setText("Beamline state")
         self.title.setAlignment(Qt.AlignmentFlag.AlignCenter)
         self.title.setFixedHeight(self.title_height)
-        self.title.setGeometry(0, 0, self.set_width, self.title_height)
+        self.title.setGeometry(0, PANEL_VMARGIN, self.set_width, self.title_height)
+        # Whole banner toggles, like TitleLabel; the +/− glyph is the indicator.
+        self.title.setCursor(Qt.CursorShape.PointingHandCursor)
+        self.title.mousePressEvent = lambda _event: self.toggle_collapsed()
 
         self.toggle_button = QPushButton("−", self)
         self.toggle_button.setObjectName("beamlineStateToggleButton")
         self.toggle_button.setToolTip("Minimise beamline state panel")
-        self.toggle_button.setFixedSize(28, 28)
-        self.toggle_button.move(self.set_width - 36, 11)
+        self.toggle_button.setFixedSize(21, 21)
+        self.toggle_button.move(
+            self.set_width - 29, PANEL_VMARGIN + (self.title_height - 21) // 2
+        )
         self.toggle_button.clicked.connect(self.toggle_collapsed)
 
         self.current_label = QLabel("Current: —", self)

src/aare/gui/panels/data_collection_settings.py

@@ -2,9 +2,11 @@ from aarecommon.math.diffraction_geometry import DiffractionGeometry
 from aarecommon.math.sample_geometry import SampleGeometryModel
 from aarecommon.models.models import DAQStatusModel
 from PySide6.QtCore import Signal, Slot
-from PySide6.QtWidgets import QFrame, QPushButton, QTabWidget, QVBoxLayout
+from PySide6.QtWidgets import QFrame, QPushButton, QTabWidget, QVBoxLayout, QWidget
 
 from aare.gui.panels.file_path_panel import FilePathPanel
+from aare.gui.panels.manual_sample_panel import ManualSamplePanel
+from aare.gui.widgets.title_label import TitleLabel, tighten_column
 from aare.gui.panels.fluorescence_data_collection import FluorescenceDataCollectionPanel
 from aare.gui.panels.raster_data_collection import RasterDataCollectionPanel
 from aare.gui.panels.rotation_data_collection import RotationDataCollectionPanel
@@ -33,6 +35,11 @@ class DataCollectionSettings(QFrame):
         self.file_path_panel = FilePathPanel(self)
         v_layout.addWidget(self.file_path_panel)
 
+        # Between Dataset path and Exp. Config., collapsible like both;
+        # main_window aliases this instead of the former bottom dock.
+        self.manual_sample_panel = ManualSamplePanel(self)
+        v_layout.addWidget(self.manual_sample_panel)
+
         self._tab_widget = QTabWidget()
 
         self.raster = RasterDataCollectionPanel(
@@ -49,13 +56,23 @@ class DataCollectionSettings(QFrame):
         self.fluo = FluorescenceDataCollectionPanel(parent=self)
         self._tab_widget.addTab(self.fluo, "XRF")
 
-        v_layout.addWidget(self._tab_widget)
-        v_layout.addStretch()
+        # Own container: TitleLabel collapse hides its siblings, so without it
+        # "Exp. Config." would also swallow the dataset path and abort button.
+        exp_config = QWidget(self)
+        exp_config_layout = QVBoxLayout(exp_config)
+        exp_config_layout.setContentsMargins(0, 0, 0, 0)
+        exp_config_layout.addWidget(TitleLabel("Exp. Config.", exp_config, collapsible=True))
+        exp_config_layout.addWidget(self._tab_widget)
+        v_layout.addWidget(exp_config)
 
         abort_button = QPushButton("Abort measurement", parent=self)
         abort_button.setStyleSheet("color: rgb(164, 0, 0);")
         abort_button.clicked.connect(self.cancel_button_clicked)
         v_layout.addWidget(abort_button)
+        # Stretch after the button: abort sits snug under the tabs instead of
+        # being pinned to the bottom of the fixed-height column.
+        v_layout.addStretch()
+        tighten_column(v_layout)
 
         raster_mgr.update_filename(self.file_path_panel.filename)
         self.screening.update_filename(self.file_path_panel.filename)

src/aare/gui/panels/file_path_panel.py

@@ -23,6 +23,10 @@ class FilePathPanel(QWidget):
     def __init__(self, parent=None):
         super().__init__(parent)
         grid_layout = QGridLayout(self)
+        # No horizontal inset: aligns the banner and fields edge-to-edge with
+        # the zero-margin Exp. Config. section below.
+        _m = grid_layout.contentsMargins()
+        grid_layout.setContentsMargins(0, _m.top(), 0, _m.bottom())
         self._sample_name = "sample"
         self._sample_id = -1
         self._dewar_pos = "None"
@@ -36,7 +40,7 @@ class FilePathPanel(QWidget):
 
         self._formatted_date = datetime.now().strftime("%Y%m%d")
 
-        grid_layout.addWidget(TitleLabel("Dataset path", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Dataset path", self, collapsible=True), 0, 0, 1, 2)
 
         grid_layout.addWidget(QLabel("Directory", parent=self), 1, 0)
         self.directory_edit = QLineEdit("{date}/{puck}/{pos}", parent=self)

src/aare/gui/panels/illumination_panel.py

@@ -13,7 +13,7 @@ class IlluminationPanel(QWidget):
         super().__init__(parent)
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Light", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Light", self, collapsible=True), 0, 0, 1, 2)
 
         front_label = QLabel("Front light", parent=self)
         front_label.setAlignment(Qt.AlignmentFlag.AlignCenter)

src/aare/gui/panels/loop_centering_panel.py

@@ -8,7 +8,7 @@ class LoopCenteringPanel(QWidget):
         super().__init__(parent)
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Loop centering", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Loop centering", self, collapsible=True), 0, 0, 1, 2)
         grid_layout.setColumnStretch(0, 1)
         grid_layout.setColumnStretch(1, 1)
 

src/aare/gui/panels/manual_sample_panel.py

@@ -18,8 +18,14 @@ class ManualSamplePanel(QWidget):
         self._pgroup = "p16371"
 
         grid_layout = QGridLayout(self)
+        # No horizontal inset: aligns the banner edge-to-edge with the Dataset
+        # path / Exp. Config. sections around it in the left column.
+        _m = grid_layout.contentsMargins()
+        grid_layout.setContentsMargins(0, _m.top(), 0, _m.bottom())
 
-        grid_layout.addWidget(TitleLabel("Manual sample", self), 0, 0, 1, 3)
+        # Kept as attribute: the Ctrl+M shortcut expands the panel via title.
+        self.title = TitleLabel("Manual sample", self, collapsible=True)
+        grid_layout.addWidget(self.title, 0, 0, 1, 3)
 
         grid_layout.addWidget(QLabel("Sample"), 1, 0)
         self._text_name = QLineEdit(self._sample_name)

src/aare/gui/panels/monochromator_panel.py

@@ -13,7 +13,7 @@ class MonochromatorPanel(QWidget):
         super().__init__(parent)
 
         grid_layout = QGridLayout(self)
-        grid_layout.addWidget(TitleLabel("Monochromator", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Monochromator", self, collapsible=True), 0, 0, 1, 2)
 
         self.mono_pitch_scan_button = QPushButton("Mono Pitch Scan", parent=self)
         self.mono_pitch_scan_button.clicked.connect(self.mono_pitch_scan.emit)

src/aare/gui/panels/omega_panel.py

@@ -29,7 +29,7 @@ class OmegaPanel(QWidget):
 
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Omega", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Omega", self, collapsible=True), 0, 0, 1, 2)
         grid_layout.setColumnStretch(0, 1)
         grid_layout.setColumnStretch(1, 1)
         omega_settings = [

src/aare/gui/panels/samcam_panel.py

@@ -35,7 +35,7 @@ class SamcamPanel(QWidget):
         # Create layout
         layout = QVBoxLayout()
 
-        layout.addWidget(TitleLabel("Sample camera", self))
+        layout.addWidget(TitleLabel("Sample camera", self, collapsible=True))
 
         # Exposure control
         exposure_layout = QHBoxLayout()

src/aare/gui/panels/smargon_panel.py

@@ -58,7 +58,7 @@ class SmargonPanel(QWidget):
 
         grid_layout = QGridLayout(self)
 
-        grid_layout.addWidget(TitleLabel("Smargon", self), 0, 0, 1, 6)
+        grid_layout.addWidget(TitleLabel("Smargon", self, collapsible=True), 0, 0, 1, 6)
 
         grid_layout.addWidget(QLabel("Chi", parent=self), 1, 0)
         self.chi_enter = NumberLineEdit(-0.2, 40, decimals=1, parent=self)

src/aare/gui/panels/zoom_panel.py

@@ -23,7 +23,7 @@ class ZoomPanel(QWidget):
             {"name": "7.5x", "value": 800},
             {"name": "12.5x", "value": 1000},
         ]
-        grid_layout.addWidget(TitleLabel("Zoom", self), 0, 0, 1, 2)
+        grid_layout.addWidget(TitleLabel("Zoom", self, collapsible=True), 0, 0, 1, 2)
         i = 2
 
         self._buttons = []

src/aare/gui/styles.py

@@ -186,19 +186,17 @@ def _original_stylesheet() -> str:
     QLabel#beamlineStateTitle {
         background-color: #4B0082;
         color: #ffffff;
-    }
-
-    QPushButton#beamlineStateToggleButton {
-        border: none;
-        border-radius: 14px;
-        background-color: rgba(255, 255, 255, 0.20);
-        color: white;
         font-size: 16px;
         font-weight: 700;
     }
 
-    QPushButton#beamlineStateToggleButton:hover {
-        background-color: rgba(255, 255, 255, 0.32);
+    /* Bare glyph to match the TitleLabel toggles: no pill background. */
+    QPushButton#beamlineStateToggleButton {
+        border: none;
+        background: transparent;
+        color: white;
+        font-size: 14px;
+        font-weight: 700;
     }
 
     QLabel#beamlineStateCurrentLabel {
@@ -430,19 +428,17 @@ def _portrait_stylesheet() -> str:
     QLabel#beamlineStateTitle {
         background-color: #132131;
         color: #F5F7FA;
-    }
-
-    QPushButton#beamlineStateToggleButton {
-        border: none;
-        border-radius: 14px;
-        background-color: rgba(255, 255, 255, 0.10);
-        color: #F5F7FA;
         font-size: 16px;
         font-weight: 700;
     }
 
-    QPushButton#beamlineStateToggleButton:hover {
-        background-color: rgba(255, 255, 255, 0.18);
+    /* Bare glyph to match the TitleLabel toggles: no pill background. */
+    QPushButton#beamlineStateToggleButton {
+        border: none;
+        background: transparent;
+        color: #F5F7FA;
+        font-size: 14px;
+        font-weight: 700;
     }
 
     QLabel#beamlineStateCurrentLabel {

src/aare/gui/widgets/title_label.py

@@ -1,12 +1,109 @@
-from PySide6.QtCore import Qt
-from PySide6.QtWidgets import QLabel
+from PySide6.QtCore import QSettings, Qt, QTimer
+from PySide6.QtWidgets import QHBoxLayout, QLabel, QLayout, QPushButton
+
+# Universal vertical rhythm between stacked panels: each panel contributes
+# PANEL_VMARGIN top and bottom, the column adds PANEL_VSPACING between them,
+# so every banner-to-banner gap is 4 + 3 + 4 = 11px in every column.
+PANEL_VSPACING = 3
+PANEL_VMARGIN = 4
+
+
+def tighten_column(layout: QLayout) -> None:
+    """Apply the universal panel gap to a column layout and its child panels.
+
+    Qt's defaults (9px margins + 6px spacing) and ad-hoc per-panel margins
+    made the gaps uneven between the left and right columns.
+    """
+    layout.setSpacing(PANEL_VSPACING)
+    for i in range(layout.count()):
+        w = layout.itemAt(i).widget()
+        if w is not None and w.layout() is not None:
+            m = w.layout().contentsMargins()
+            w.layout().setContentsMargins(m.left(), PANEL_VMARGIN, m.right(), PANEL_VMARGIN)
 
 
 class TitleLabel(QLabel):
-    def __init__(self, text: str, parent=None):
+    def __init__(self, text: str, parent=None, collapsible: bool = False):
         super().__init__(parent)
-        self.setText(f"<H3>{text}</H3>")
-        self.setStyleSheet("background-color: #4B0082; color: #ffffff;")
+        # Plain text + QSS font instead of <H3>: rich-text heading margins
+        # would clip vertically in the halved banner height.
+        self.setText(text)
+        # Scoped selector: an unscoped widget stylesheet propagates to child
+        # widgets and would paint the toggle button solid purple, overriding
+        # the app QSS.
+        self.setStyleSheet(
+            "TitleLabel { background-color: #4B0082; color: #ffffff;"
+            " font-size: 16px; font-weight: 700; }"
+        )
         self.setAlignment(Qt.AlignmentFlag.AlignCenter)
 
-        self.setFixedHeight(50)
+        # Half the original 50px: the full-height banner wasted vertical space.
+        self.setFixedHeight(25)
+
+        self._collapsible = collapsible
+        if not collapsible:
+            return
+
+        self._collapsed = False
+        # ponytail: settings key is the title text — unique across panels;
+        # renaming a title just resets that panel to expanded once.
+        self._settings_key = f"panel_collapsed/{text}"
+
+        self.toggle_button = QPushButton("−", self)
+        # Bare glyph, no pill: the shared beamlineStateToggleButton QSS paints
+        # a translucent white background, which is unwanted on these banners.
+        self.toggle_button.setStyleSheet(
+            "QPushButton { background: transparent; border: none;"
+            " color: #ffffff; font-size: 14px; font-weight: 700; }"
+        )
+        self.toggle_button.setToolTip("Minimise panel")
+        self.toggle_button.setFixedSize(21, 21)
+        self.toggle_button.setCursor(Qt.CursorShape.PointingHandCursor)
+        self.toggle_button.clicked.connect(self.toggle_collapsed)
+
+        button_layout = QHBoxLayout(self)
+        button_layout.setContentsMargins(0, 0, 8, 0)
+        button_layout.addStretch()
+        button_layout.addWidget(self.toggle_button)
+
+        self.setCursor(Qt.CursorShape.PointingHandCursor)
+
+        settings = QSettings("PSI", "AareGUI")
+        if settings.value(self._settings_key, False, type=bool):
+            self._collapsed = True
+            # Deferred: the panel adds its other widgets after constructing
+            # the TitleLabel, so siblings don't exist yet.
+            QTimer.singleShot(0, self._apply_collapsed)
+
+    def mousePressEvent(self, event):
+        if self._collapsible:
+            self.toggle_collapsed()
+        super().mousePressEvent(event)
+
+    def expand(self) -> None:
+        if self._collapsible and self._collapsed:
+            self.toggle_collapsed()
+
+    def toggle_collapsed(self) -> None:
+        self._collapsed = not self._collapsed
+        self._apply_collapsed()
+        QSettings("PSI", "AareGUI").setValue(self._settings_key, self._collapsed)
+
+    def _apply_collapsed(self) -> None:
+        parent = self.parentWidget()
+        if parent is None or parent.layout() is None:
+            return
+        self._set_visible(parent.layout(), not self._collapsed)
+        self.toggle_button.setText("+" if self._collapsed else "−")
+        self.toggle_button.setToolTip("Restore panel" if self._collapsed else "Minimise panel")
+
+    def _set_visible(self, layout: QLayout, visible: bool) -> None:
+        # Recursive: panels like SamcamPanel nest sub-layouts via addLayout.
+        for i in range(layout.count()):
+            item = layout.itemAt(i)
+            widget = item.widget()
+            if widget is not None:
+                if widget is not self:
+                    widget.setVisible(visible)
+            elif item.layout() is not None:
+                self._set_visible(item.layout(), visible)

tests/unit/gui/test_title_label.py

@@ -0,0 +1,72 @@
+from PySide6.QtCore import QSettings
+from PySide6.QtWidgets import QGridLayout, QHBoxLayout, QPushButton, QWidget
+
+from aare.gui.widgets.title_label import TitleLabel
+
+# Unique title so the test never clashes with real panel settings.
+TITLE = "TitleLabelTestPanel"
+KEY = f"panel_collapsed/{TITLE}"
+
+
+def _remove_key():
+    QSettings("PSI", "AareGUI").remove(KEY)
+
+
+def _build_panel(qtbot):
+    panel = QWidget()
+    qtbot.addWidget(panel)
+    grid = QGridLayout(panel)
+    title = TitleLabel(TITLE, panel, collapsible=True)
+    grid.addWidget(title, 0, 0, 1, 2)
+    direct_child = QPushButton("direct", panel)
+    grid.addWidget(direct_child, 1, 0)
+    nested = QHBoxLayout()
+    nested_child = QPushButton("nested", panel)
+    nested.addWidget(nested_child)
+    grid.addLayout(nested, 1, 1)
+    return panel, title, direct_child, nested_child
+
+
+def test_toggle_hides_children_and_persists(qtbot):
+    _remove_key()
+    try:
+        panel, title, direct_child, nested_child = _build_panel(qtbot)
+        expanded_height = panel.sizeHint().height()
+
+        title.toggle_collapsed()
+        assert direct_child.isHidden()
+        assert nested_child.isHidden()
+        assert not title.isHidden()
+        assert panel.sizeHint().height() < expanded_height
+        assert title.toggle_button.text() == "+"
+        assert QSettings("PSI", "AareGUI").value(KEY, False, type=bool) is True
+
+        title.toggle_collapsed()
+        assert not direct_child.isHidden()
+        assert not nested_child.isHidden()
+        assert title.toggle_button.text() == "−"
+        assert QSettings("PSI", "AareGUI").value(KEY, False, type=bool) is False
+    finally:
+        _remove_key()
+
+
+def test_collapsed_state_restored_on_construction(qtbot):
+    QSettings("PSI", "AareGUI").setValue(KEY, True)
+    try:
+        panel, title, direct_child, nested_child = _build_panel(qtbot)
+        # Restore is deferred with a 0 ms timer (siblings don't exist yet at
+        # TitleLabel construction), so let the event loop run once.
+        qtbot.waitUntil(lambda: direct_child.isHidden(), timeout=1000)
+        assert nested_child.isHidden()
+        assert title.toggle_button.text() == "+"
+    finally:
+        _remove_key()
+
+
+def test_not_collapsible_by_default(qtbot):
+    panel = QWidget()
+    qtbot.addWidget(panel)
+    grid = QGridLayout(panel)
+    title = TitleLabel("Plain", panel)
+    grid.addWidget(title, 0, 0)
+    assert not hasattr(title, "toggle_button")