wxGLCanvasEGL::IsShownOnScreen() regression under Wayland

[vadz]

After thinking about this for a while I think I may have found a small oversight.
IsShownOnScreen() uses m_readyToDraw as one of the checks under Wayland. Before this PR, m_readyToDraw was set to true once after first wl_frame_callback_handler. After this PR now the m_readyToDraw is toggled after each frame.

IsShownOnScreen() probably shouldn't flap at 60hz?

I hacked it use gtk_window_is_visible() for IsShownOnScreen check and in my limited testing Kicad renders a bit better.

diff --git a/src/unix/glegl.cpp b/src/unix/glegl.cpp
index c35273caddaa..0f009e3f4fb8 100644
--- a/src/unix/glegl.cpp
+++ b/src/unix/glegl.cpp
@@ -697,12 +697,13 @@ bool wxGLCanvasEGL::SwapBuffers()
 bool wxGLCanvasEGL::IsShownOnScreen() const
 {
     wxDisplayInfo info = wxGetDisplayInfo();
+    GdkWindow* const window = GTKGetDrawingWindow();
     switch ( info.type )
     {
         case wxDisplayX11:
             return GetXWindow() && wxGLCanvasBase::IsShownOnScreen();
         case wxDisplayWayland:
-            return m_readyToDraw && wxGLCanvasBase::IsShownOnScreen();
+            return gtk_window_is_visible(window) && wxGLCanvasBase::IsShownOnScreen();
         default:
             return false;
     }

Originally posted by @artizirk in #23554 (comment)

[artizirk]

Sorry for being absent for quite a long time, life got too busy.

Thanks @artizirk, I think you're right and we shouldn't be using m_readyToDraw here, but I'm a bit confused as to how does it actually change anything for redrawing: we don't seem to use IsShownOnScreen() anywhere under Wayland (under X11 we use it in SwapBuffers()).

People are working on trying to get KiCad running on Wayland which is the reason why bunch of interesting bugs are cropping up when testing things (me included).

So, as far as I understand as a side observer. Most of the canvas rendering in Kicad is done via their Graphics Abstraction Layer (include/gal/graphics_abstraction_layer.h). Both Cairo and OpenGL GAL backends use IsShownOnScreen() inside their IsVisible() implementation. IsVisible() in turn is used in a whole lot of places to gate if things should be updated on the screen. (grep -r 'IsVisible()' | wc -l: 159) And thats why I think broken IsShownOnScreen affects KiCad rendering but only under Wayland. (There is also a chance that I misunderstood how wxWidgets and KiCad rendering works...)