Also use windowNumberAtPoint: to test if we're in the popoverWindow.

Rebel/RBLPopover.m

@@ -332,7 +332,7 @@ static CGFloat RBLRectsGetMedianY(CGRect r1, CGRect r2) {
 			RBLPopover *strongSelf = weakSelf;
 			if (strongSelf.popoverWindow == nil) return;
 			BOOL shouldClose = NO;
-			BOOL mouseInPopoverWindow = NSPointInRect(NSEvent.mouseLocation, strongSelf.popoverWindow.frame);
+			BOOL mouseInPopoverWindow = ([NSWindow windowNumberAtPoint:NSEvent.mouseLocation belowWindowWithWindowNumber:0] == strongSelf.popoverWindow.windowNumber);
 			if (strongSelf.behavior == RBLPopoverBehaviorTransient) {
 				shouldClose = !mouseInPopoverWindow;
 			} else {