Guard OpenGL mode on native Wayland

MainForm.pas

@@ -35,6 +35,7 @@ uses
   CATEngine, CATSerial, CATTcp,
   SpectrumView, SpectrumViewOpengl,
   StatusBar,
+  PlatformUtils,
   WinFirewall;
 
 const
@@ -1469,6 +1470,22 @@ begin
   FSplitterDrag  := False;
 
   FUseOpenGLSpectrum := HasOpenGLSpectrumSwitch;
+  if FUseOpenGLSpectrum and (not QtPlatformAllowsOpenGLControls) then
+  begin
+    MessageDlg('OpenGL rendering disabled',
+      'OpenGL rendering is not available in the current Qt Wayland mode.' + LineEnding +
+      LineEnding +
+      'The Lazarus/LCL Qt6 OpenGL control used by EWSDR requires an X11 display handle, ' +
+      'but the native Wayland backend does not provide one. Using it here can cause an access violation during startup.' +
+      LineEnding +
+      LineEnding +
+      'To run EWSDR with OpenGL rendering, start it through XWayland:' + LineEnding +
+      'QT_QPA_PLATFORM=xcb ./ewsdr --opengl' + LineEnding +
+      LineEnding +
+      'OpenGL rendering will be disabled for this session.',
+      mtWarning, [mbOK], 0);
+    FUseOpenGLSpectrum := False;
+  end;
   if FUseOpenGLSpectrum then
     FWaterfallFrameInterval := 1;
   if FUseOpenGLSpectrum then