added and use a mapping DescType to MDISubType

grum/mainwin.py

@@ -14,6 +14,12 @@ from .shortcut import shortcut
 from .webview import WebView
 
 
+DESC_TYPE_TO_MDI_SUB_TYPE = {
+    ImageDescription: MDISubImage,
+    PlotDescription:  MDISubPlot
+}
+
+
 class MainWindow(QMainWindow):
 
     sig_make_new_plot  = pyqtSignal(str, PlotDescription)
@@ -248,7 +254,8 @@ class MainWindow(QMainWindow):
         item.timestamps.access.update()
         item.set_alarm(False)
         name, desc = item.key, item.value
-        MDISubType = MDISubImage if isinstance(desc, ImageDescription) else MDISubPlot #TODO
+        DescType = type(desc)
+        MDISubType = DESC_TYPE_TO_MDI_SUB_TYPE[DescType]
         self.activate_or_make_subwin(MDISubType, name, desc)
 
     def plot_multiple_items(self, items):