improve doxygen documentation of PMsgBox.*

src/classes/PMsgBox.cpp

@@ -29,10 +29,42 @@
 
 #include "PMsgBox.h"
 
+//--------------------------------------------------------------------------
+// Constructor
+//--------------------------------------------------------------------------
+/**
+ * \brief Constructor that creates and displays the message box GUI.
+ *
+ * This constructor performs the following steps:
+ * 1. Creates a scrollable list box widget
+ * 2. Parses the error message string by splitting at newline characters
+ * 3. Populates the list box with individual message lines
+ * 4. Creates an Exit button with callback to DoExit()
+ * 5. Configures layout and displays the window
+ *
+ * The message parsing algorithm:
+ * - Adds an initial empty line
+ * - Splits the input string at each '\n' character
+ * - Each substring becomes a separate list box entry
+ * - Handles multi-line messages gracefully
+ *
+ * GUI Layout:
+ * - List box: 600x200 pixels, expandable, with 5-pixel margins
+ * - Button frame: Fixed width (150px), contains Exit button
+ * - Window title: "Error Message"
+ *
+ * \param errMsg Multi-line error message string with '\n' separators
+ * \param p Parent window pointer (typically gClient->GetRoot())
+ * \param w Initial window width in pixels
+ * \param h Initial window height in pixels
+ *
+ * \note The window is automatically mapped (displayed) after construction
+ * \note The list box ID is set to 89 (ROOT widget identifier)
+ */
 PMsgBox::PMsgBox(const std::string errMsg, const TGWindow *p, UInt_t w, UInt_t h) : TGMainFrame(p, w, h)
 {
    fListBox = new TGListBox(this, 89);
-   
+
    // feed list box with errMsg
    size_t start = 0;
    size_t end = errMsg.find("\n");
@@ -45,7 +77,7 @@ PMsgBox::PMsgBox(const std::string errMsg, const TGWindow *p, UInt_t w, UInt_t h
      end = errMsg.find("\n", start);
      fListBox->AddEntry(tok.c_str(), i++);
    }
-   
+
    fListBox->Resize(600, 200);
    AddFrame(fListBox, new TGLayoutHints(kLHintsTop | kLHintsLeft | kLHintsExpandX | kLHintsExpandY, 5, 5, 5, 5));
 
@@ -67,11 +99,45 @@ PMsgBox::PMsgBox(const std::string errMsg, const TGWindow *p, UInt_t w, UInt_t h
    MapWindow();
 }
 
+//--------------------------------------------------------------------------
+// Destructor
+//--------------------------------------------------------------------------
+/**
+ * \brief Destructor that cleans up the message box resources.
+ *
+ * The ROOT framework automatically handles cleanup of GUI components
+ * (list box, buttons, frames) through the TGMainFrame destructor chain,
+ * so no explicit cleanup is required here.
+ *
+ * \note GUI widgets are managed by ROOT and are automatically deleted
+ *       when the main frame is destroyed
+ */
 PMsgBox::~PMsgBox()
 {
-  // nothing to be done here?
+  // nothing to be done here - ROOT handles GUI cleanup automatically
 }
 
+//--------------------------------------------------------------------------
+// DoExit
+//--------------------------------------------------------------------------
+/**
+ * \brief Exit button callback that terminates the application.
+ *
+ * This method is invoked when the user clicks the Exit button.
+ * It terminates the entire ROOT application with exit code 0,
+ * which causes a clean shutdown of the program.
+ *
+ * The method is connected to the Exit button's "Pressed()" signal
+ * in the constructor via ROOT's signal/slot mechanism:
+ * \code
+ * exit->Connect("Pressed()", "PMsgBox", this, "DoExit()");
+ * \endcode
+ *
+ * \note This terminates the entire application, not just the message box window
+ * \note Exit code 0 indicates successful termination
+ *
+ * \see gApplication for ROOT's global application object
+ */
 void PMsgBox::DoExit()
 {
    gApplication->Terminate(0);

src/include/PMsgBox.h

@@ -38,14 +38,67 @@
 #include <TGListBox.h>
 #include <TList.h>
 
+//--------------------------------------------------------------------------
+/**
+ * \brief GUI message box for displaying error messages and warnings.
+ *
+ * PMsgBox is a ROOT-based GUI window that displays multi-line error messages
+ * in a scrollable list box. It provides a simple, modal-like interface for
+ * showing diagnostic information to the user.
+ *
+ * The message box:
+ * - Parses multi-line error messages (separated by newline characters)
+ * - Displays each line in a scrollable list box
+ * - Provides an Exit button that terminates the application
+ * - Uses ROOT's TGMainFrame for window management
+ *
+ * Typical use case:
+ * \code
+ * std::string errorMsg = "Error parsing file:\nLine 42: Invalid syntax\nAborting...";
+ * PMsgBox msgBox(errorMsg, gClient->GetRoot(), 640, 240);
+ * \endcode
+ *
+ * \see TGMainFrame for the base class
+ */
 class PMsgBox : public TGMainFrame {
 
 private:
-   TGListBox *fListBox;
+   TGListBox *fListBox;  ///< List box widget displaying error message lines
 
 public:
+   //-----------------------------------------------------------------------
+   /**
+    * \brief Constructor that creates and displays the message box window.
+    *
+    * Creates a GUI window containing:
+    * - A scrollable list box with the parsed error message
+    * - An Exit button that terminates the application
+    *
+    * The error message is split at newline characters, and each line is
+    * displayed as a separate entry in the list box.
+    *
+    * \param errMsg Multi-line error message string (lines separated by '\n')
+    * \param p Parent window (typically gClient->GetRoot())
+    * \param w Window width in pixels
+    * \param h Window height in pixels
+    */
    PMsgBox(const std::string errMsg, const TGWindow *p, UInt_t w, UInt_t h);
+
+   //-----------------------------------------------------------------------
+   /**
+    * \brief Destructor that cleans up the message box resources.
+    */
    ~PMsgBox() override;
+
+   //-----------------------------------------------------------------------
+   /**
+    * \brief Exit button callback that terminates the application.
+    *
+    * This method is called when the user clicks the Exit button.
+    * It terminates the entire application with exit code 0.
+    *
+    * \note This will exit the entire application, not just close the window
+    */
    void DoExit();
 
    ClassDefOverride(PMsgBox, 0)