cocoa: fix cursor hiding at the top of the screen in fullscreen

even before the recent refactor the cursor was hidden when moving it to
the top of the screen in fullscreen and placing it on top of the now
visible menu bar.

we need to know when the menu bar is hidden so we don’t create a
‘dead zone’ at the top of the screen where the cursor can’t be hidden.
to determine when the menu bar is visible, and with that the title bar,
we get the height of the menu bar. the height is always 0 when hidden.

furthermore there is no way to get the title bar directly and with that
its height. so we calculate the frame rect of a NSWindowStyleMaskTitled
window from a CGRectZero content frame. the resulting height is the
height of a title bar.

with that we can exclude the top area for the cursor hiding and can be
certain when the menu bar is not hidden.

video/out/cocoa/events_view.m

@@ -86,7 +86,19 @@
 
 - (BOOL)containsMouseLocation
 {
+    CGFloat topMargin = 0.0;
+    CGFloat menuBarHeight = [[NSApp mainMenu] menuBarHeight];
+
+    // menuBarHeight is 0 when menu bar is hidden in fullscreen
+    // 1pt to compensate of the black line beneath the menu bar
+    if ([self.adapter isInFullScreenMode] && menuBarHeight > 0) {
+        NSRect tr = [NSWindow frameRectForContentRect:CGRectZero
+                                            styleMask:NSWindowStyleMaskTitled];
+        topMargin = tr.size.height + 1 + menuBarHeight;
+    }
+
     NSRect vF  = [[self.window screen] frame];
+    vF.size.height -= topMargin;
     NSRect vFW = [self.window convertRectFromScreen:vF];
     NSRect vFV = [self convertRect:vFW fromView:nil];
     NSPoint pt = [self convertPoint:[self mouseLocation] fromView:nil];