Fix #116774 - when in background Moz shouldn't directly test mouse button state to decide if it needs to process events (was causing Moz to peg CPU when mouse was down and it was in background). r=ccarlen,pinkerton,sr=sfraser,a=asa

widget/src/mac/nsMacMessagePump.cpp

@@ -374,7 +374,10 @@ PRBool nsMacMessagePump::GetEvent(EventRecord &theEvent)
   
   // Make sure we call WNE if we have user events, or the mouse is down
   EventRecord tempEvent;
-  PRBool havePendingEvent = ::EventAvail(kEventAvailMask, &tempEvent) || !(tempEvent.modifiers & btnState);
+  // When checking btnState make sure to test if we're in the background
+  PRBool havePendingEvent =
+    ::EventAvail(kEventAvailMask, &tempEvent) ||
+    (!(tempEvent.modifiers & btnState) && nsToolkit::IsAppInForeground());
   
   // don't call more than once every 4 ticks
   if (!havePendingEvent && (::TickCount() < sNextWNECall))