Bypass transparency optimization with HC themes.

Don't use transparency optimization for theme items in Windows 8
or later with a high contrast theme in use.

See MoonchildProductions/Pale-Moon#1591

1 files changed, 4 insertions, 1 deletions

diff --git a/widget/windows/nsNativeThemeWin.cpp b/widget/windows/nsNativeThemeWin.cpp
index 8950dcf90..475ebce94 100644
--- a/widget/windows/nsNativeThemeWin.cpp
+++ b/widget/windows/nsNativeThemeWin.cpp
@@ -1360,7 +1360,10 @@ nsNativeThemeWin::GetThemePartAndState(nsIFrame* aFrame, uint8_t aWidgetType,
 static bool
 AssumeThemePartAndStateAreTransparent(int32_t aPart, int32_t aState)
 {
-  if (aPart == MENU_POPUPITEM && aState == MBI_NORMAL) {
+  // When using a high contrast theme on Windows 8 or later, we can't
+  // use this optimization.
+  if (!(IsWin8OrLater() && nsUXThemeData::IsHighContrastOn()) &&
+      aPart == MENU_POPUPITEM && aState == MBI_NORMAL) {
     return true;
   }
   return false;