[PATCH v2 1/1] winex11.drv: Move the dummy parent window to (0, 0).

[Zhiyi Zhang]

From: Zhiyi Zhang

Move the dummy parent window from (-1, -1) to (0, 0) so that the window is considered visible by
Wayland. The X11 window region is set to an empty rectangle so that the window is still in fact
invisible. If Xshape support is not compiled in, then fall back to using (-1, -1).

This fixes poor performance when running Office 2016 on Xwayland. It's caused by glXWaitForSbcOML()
in glxdrv_wglSwapBuffers() taking 1 second every time it gets called. The timeout is from
TIMER_LEN_FLIP (1000ms) in xwl_present_reset_timer() in the xserver source code hw/xwayland/xwayland-present.c.
Xwayland doesn't actually know when a frame is visible on screen[1][2]. It relies on a timer to
simulate the process and when the window is invisible it uses a timer with a 1000ms timeout. This
patch makes the dummy parent window visible so that Xwayland will use the timer with a 17ms timeout(~60fps),
which also means that there will still be a 60fps limit for some windows when running on Xwayland.

[1]: https://gitlab.freedesktop.org/xorg/xserver/-/issues/971
[2]: https://gitlab.freedesktop.org/xorg/xserver/-/issues/973
---
 dlls/winex11.drv/window.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/dlls/winex11.drv/window.c b/dlls/winex11.drv/window.c
index 974bd376fe6..1819d4b4d8f 100644
--- a/dlls/winex11.drv/window.c
+++ b/dlls/winex11.drv/window.c
@@ -1512,9 +1512,22 @@ Window get_dummy_parent(void)
         attrib.override_redirect = True;
         attrib.border_pixel = 0;
         attrib.colormap = default_colormap;
+
+#ifdef HAVE_LIBXSHAPE
+        {
+            static XRectangle empty_rect;
+            dummy_parent = XCreateWindow( gdi_display, root_window, 0, 0, 1, 1, 0,
+                                          default_visual.depth, InputOutput, default_visual.visual,
+                                          CWColormap | CWBorderPixel | CWOverrideRedirect, &attrib );
+            XShapeCombineRectangles( gdi_display, dummy_parent, ShapeBounding, 0, 0, &empty_rect, 1,
+                                     ShapeSet, YXBanded );
+        }
+#else
         dummy_parent = XCreateWindow( gdi_display, root_window, -1, -1, 1, 1, 0, default_visual.depth,
                                       InputOutput, default_visual.visual,
                                       CWColormap | CWBorderPixel | CWOverrideRedirect, &attrib );
+        WARN("Xshape support is not compiled in. Applications under XWayland may have poor performance.");
+#endif
         XMapWindow( gdi_display, dummy_parent );
     }
     return dummy_parent;