improve the doxygen documentation of the plotter-part of mupp.

src/musredit_qt6/mupp/plotter/mupp_plot.cpp

@@ -5,6 +5,21 @@
   Author: Andreas Suter
   e-mail: andreas.suter@psi.ch
 
+  This is the main entry point for the mupp_plot application, a standalone
+  ROOT-based plotting program that works in conjunction with the mupp GUI.
+
+  The program:
+  - Takes a mupp instance number (0-255) as a command-line argument
+  - Reads plot styling configuration from mupp_startup.xml
+  - Creates a ROOT application with a PMuppCanvas for displaying plots
+  - Establishes IPC communication with the mupp GUI via message queues
+  - Monitors for plot data updates and refreshes the display accordingly
+  - Provides interactive features (zoom, export, line/marker toggle)
+
+  The mupp_plot application runs as a separate process from the main mupp
+  GUI, allowing plots to be displayed and manipulated independently while
+  maintaining synchronization with the data analysis workflow.
+
 ***************************************************************************/
 
 /***************************************************************************
@@ -39,10 +54,22 @@
 
 //--------------------------------------------------------------------------
 /**
- * @brief main
- * @param argc
- * @param argv
- * @return
+ * @brief Main entry point for the mupp_plot application.
+ *
+ * Initializes the ROOT plotting environment, reads configuration from
+ * mupp_startup.xml, creates the canvas, and runs the ROOT event loop.
+ *
+ * The program flow:
+ * 1. Validates command-line arguments (mupp instance number)
+ * 2. Parses mupp_startup.xml for marker styles, sizes, and colors
+ * 3. Creates a TApplication and PMuppCanvas
+ * 4. Sets up signal/slot connections for window management
+ * 5. Runs the ROOT event loop
+ * 6. Cleans up resources on exit
+ *
+ * @param argc number of command-line arguments (must be 2)
+ * @param argv command-line arguments array; argv[1] must be instance number (0-255)
+ * @return exit status: 0 on success, -1 if argc != 2, -2 if instance number out of range
  */
 int main(int argc, char *argv[])
 {