On Windows, replace all calls to UpdateWindow by calls to InvalidateRgn

This avoids directly sending a WM_PAINT message,
which might cause buffering of RedrawRequested events.

We don't want to buffer RedrawRequested events because:
- we wan't to handle RedrawRequested during processing of WM_PAINT messages
- state transitionning is broken when handling buffered RedrawRequested events

Fixes rust-windowing#1469

Author: filnet

src/platform_impl/windows/util.rs

@@ -116,7 +116,7 @@ pub(crate) fn set_inner_size_physical(window: HWND, x: u32, y: u32) {
                 | winuser::SWP_NOMOVE
                 | winuser::SWP_NOACTIVATE,
         );
-        winuser::UpdateWindow(window);
+        winuser::InvalidateRgn(window, ptr::null_mut(), 0);
     }
 }
 

src/platform_impl/windows/window.rs

@@ -187,7 +187,7 @@ impl Window {
                     | winuser::SWP_NOSIZE
                     | winuser::SWP_NOACTIVATE,
             );
-            winuser::UpdateWindow(self.window.0);
+            winuser::InvalidateRgn(self.window.0, ptr::null_mut(), 0);
         }
     }
 
@@ -506,7 +506,7 @@ impl Window {
                             size.1 as i32,
                             winuser::SWP_ASYNCWINDOWPOS | winuser::SWP_NOZORDER,
                         );
-                        winuser::UpdateWindow(window.0);
+                        winuser::InvalidateRgn(window.0, ptr::null_mut(), 0);
                     }
                 }
                 None => {
@@ -532,7 +532,7 @@ impl Window {
                                     | winuser::SWP_NOZORDER
                                     | winuser::SWP_NOACTIVATE,
                             );
-                            winuser::UpdateWindow(window.0);
+                            winuser::InvalidateRgn(window.0, ptr::null_mut(), 0);
                         }
                     }
                 }

src/platform_impl/windows/window_state.rs

@@ -266,7 +266,7 @@ impl WindowFlags {
                         | winuser::SWP_NOSIZE
                         | winuser::SWP_NOACTIVATE,
                 );
-                winuser::UpdateWindow(window);
+                winuser::InvalidateRgn(window, ptr::null_mut(), 0);
             }
         }