WaylandBackend: Ignore events on unknown surfaces

wl_pointer enter/leave events are being processed for what I think are libdecor surfaces, this
means the surface user_data is being miscast as CWaylandPlane.

src/Backends/WaylandBackend.cpp

@@ -590,6 +590,16 @@ namespace gamescope
             return &iter->second;
         }
 
+        bool IsSurfacePlane(wl_surface *pSurface)
+        {
+            for ( uint32_t i = 0; i < 8; i++ )
+            {
+                if (m_Planes[i].GetSurface() == pSurface)
+                    return true;
+            }
+            return false;
+        }
+
         bool CurrentDisplaySupportsVRR() const { return HostCompositorIsCurrentlyVRR(); }
         wl_region *GetFullRegion() const { return m_pFullRegion; }
 
@@ -2573,6 +2583,9 @@ namespace gamescope
 
     void CWaylandInputThread::Wayland_Pointer_Enter( wl_pointer *pPointer, uint32_t uSerial, wl_surface *pSurface, wl_fixed_t fSurfaceX, wl_fixed_t fSurfaceY )
     {
+        if (!m_pBackend->IsSurfacePlane(pSurface))
+           return;
+
         CWaylandPlane *pPlane = (CWaylandPlane *)wl_surface_get_user_data( pSurface );
         if ( !pPlane )
             return;
@@ -2584,6 +2597,9 @@ namespace gamescope
     }
     void CWaylandInputThread::Wayland_Pointer_Leave( wl_pointer *pPointer, uint32_t uSerial, wl_surface *pSurface )
     {
+        if (!m_pBackend->IsSurfacePlane(pSurface))
+           return;
+
         CWaylandPlane *pPlane = (CWaylandPlane *)wl_surface_get_user_data( pSurface );
         if ( !pPlane )
             return;