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

src/musredit_qt6/mupp/plotter/PMuppStartupHandler.cpp

@@ -5,6 +5,26 @@
   Author: Andreas Suter
   e-mail: andreas.suter@psi.ch
 
+  This file implements the PMuppStartupHandler class, a SAX parser handler
+  for reading mupp_startup.xml configuration files.
+
+  The implementation:
+  - Searches for mupp_startup.xml in current directory or $HOME/.musrfit/mupp/
+  - Parses marker styles, sizes, and colors using ROOT's SAX parser
+  - Generates random defaults if file is not found or lists are incomplete
+  - Provides a parseXmlFile() utility function for reliable XML parsing
+
+  SAX Parsing Flow:
+  1. OnStartDocument() - initialize state
+  2. OnStartElement() - detect marker/color blocks
+  3. OnCharacters() - extract numeric values and color names
+  4. OnEndElement() - finalize current block
+  5. OnEndDocument() - validate lists with CheckLists()
+
+  The CheckLists() method ensures all three lists (marker styles, sizes,
+  colors) have the same length, generating random values as needed for
+  consistency.
+
 ***************************************************************************/
 
 /***************************************************************************
@@ -79,7 +99,13 @@ int parseXmlFile(TSAXParser *saxParser, const char *startup_path_name)
 // Constructor
 //--------------------------------------------------------------------------
 /**
- * @brief PMuppStartupHandler::PMuppStartupHandler
+ * @brief Constructor that searches for mupp_startup.xml configuration file.
+ *
+ * Search order:
+ * 1. ./mupp_startup.xml (current directory)
+ * 2. $HOME/.musrfit/mupp/mupp_startup.xml (user configuration directory)
+ *
+ * Sets fStartupFileFound and fStartupFilePath based on search results.
  */
 PMuppStartupHandler::PMuppStartupHandler()
 {
@@ -116,7 +142,9 @@ PMuppStartupHandler::PMuppStartupHandler()
 // Destructor
 //--------------------------------------------------------------------------
 /**
- * @brief PMuppStartupHandler::~PStartupHandler
+ * @brief Destructor that cleans up style list vectors.
+ *
+ * Clears all marker style, size, and color list vectors to free memory.
  */
 PMuppStartupHandler::~PMuppStartupHandler()
 {