fix issues with resizing fullscreen windows

panda/src/display/graphicsWindow.cxx

@@ -566,6 +566,7 @@ set_properties_now(WindowProperties &properties) {
 
         // And mark the window closed.
         _properties.set_open(false);
+        _is_valid = false;
       }
 
     } else {

panda/src/dxgsg8/wdxGraphicsWindow8.cxx

@@ -437,6 +437,10 @@ handle_reshape() {
 ////////////////////////////////////////////////////////////////////
 bool wdxGraphicsWindow8::
 do_fullscreen_resize(int x_size, int y_size) {
+  if (!WinGraphicsWindow::do_fullscreen_resize(x_size, y_size)) {
+    return false;
+  }
+
   bool bCouldntFindValidZBuf;
   D3DFORMAT pixFmt;
   bool bNeedZBuffer = (_wcontext._presentation_params.EnableAutoDepthStencil != false);

panda/src/dxgsg9/wdxGraphicsWindow9.cxx

@@ -436,6 +436,10 @@ handle_reshape() {
 ////////////////////////////////////////////////////////////////////
 bool wdxGraphicsWindow9::
 do_fullscreen_resize(int x_size, int y_size) {
+  if (!WinGraphicsWindow::do_fullscreen_resize(x_size, y_size)) {
+    return false;
+  }
+
   bool bCouldntFindValidZBuf;
   D3DFORMAT pixFmt;
   bool bNeedZBuffer = (_wcontext._presentation_params.EnableAutoDepthStencil != false);