Fix DSView icon missing from COSMIC desktop taskbar

On Wayland (e.g. COSMIC), running apps are matched to their desktop
entry via the Wayland app-id. Qt derives the app-id from
QGuiApplication::desktopFileName() if set, otherwise falls back to the
application name ("DSView"). Since the desktop file is named
"dsview.desktop", the case mismatch prevented COSMIC from matching the
running app to its entry.

Fixed by calling setDesktopFileName("dsview") to explicitly match the
desktop file name. Also moved the desktop file install destination from
the hardcoded /usr/share/applications to the cmake install prefix
(share/applications) for consistency with other installed files.
Added StartupWMClass=DSView for X11 compatibility.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: TheCodeSharman

CMakeLists.txt

@@ -669,7 +669,7 @@ install(FILES DSView/icons/logo.svg DESTINATION share/icons/hicolor/scalable/app
 install(FILES DSView/icons/logo.svg DESTINATION share/pixmaps RENAME dsview.svg)
 
 if(CMAKE_SYSTEM_NAME MATCHES "Linux")	
-	install(FILES DSView/DSView.desktop DESTINATION /usr/share/applications RENAME dsview.desktop)
+	install(FILES DSView/DSView.desktop DESTINATION share/applications RENAME dsview.desktop)
 
 	add_compile_definitions(_DEFAULT_SOURCE)
 

DSView/DSView.desktop

@@ -6,5 +6,6 @@ Comment=GUI Program for DreamSourceLab USB-based Instruments
 TryExec=DSView
 Exec=DSView
 Icon=dsview
+StartupWMClass=DSView
 Terminal=false
 Categories=Development;Electronics;Qt;

DSView/main.cpp

@@ -174,6 +174,7 @@ bool bHighScale = true;
     QApplication::setApplicationName("DSView");
     QApplication::setOrganizationName("DreamSourceLab");
     QApplication::setOrganizationDomain("www.DreamSourceLab.com");
+    QApplication::setDesktopFileName("dsview");
 
 	//----------------------init log
 	dsv_log_init(); // Don't call before QApplication be inited