Attempt at working around another 10.14 drawing issue (#3271)

Frameworks/PSMTabBar/PSMRolloverButton.h

@@ -16,19 +16,19 @@
 }
 
 // the regular image
-- (void)setUsualImage:(nullable NSImage *)newImage;
-- (nullable NSImage *)usualImage;
+- (void)setUsualImage:(NSImage *)newImage;
+- (NSImage *)usualImage;
 
 // the rollover image
-- (void)setRolloverImage:(nullable NSImage *)newImage;
-- (nullable NSImage *)rolloverImage;
+- (void)setRolloverImage:(NSImage *)newImage;
+- (NSImage *)rolloverImage;
 
 // tracking rect for mouse events
-- (void)rolloverFrameDidChange:(nonnull NSNotification *)notification;
+- (void)rolloverFrameDidChange:(NSNotification *)notification;
 - (void)addTrackingRect;
 - (void)removeTrackingRect;
 
-- (void)mouseEntered:(nullable NSEvent *)event;
-- (void)mouseExited:(nullable NSEvent *)event;
+- (void)mouseEntered:(NSEvent *)event;
+- (void)mouseExited:(NSEvent *)event;
 
 @end

Frameworks/PSMTabBar/PSMRolloverButton.m

@@ -118,15 +118,15 @@ - (void)removeTrackingRect
 }
 
 // override for rollover effect
-- (void)mouseEntered:(nullable NSEvent *)event
+- (void)mouseEntered:(NSEvent *)event
 {
     // set rollover image
     [self setImage:_rolloverImage];
 
 	[super mouseEntered:event];
 }
 
-- (void)mouseExited:(nullable NSEvent *)event
+- (void)mouseExited:(NSEvent *)event
 {
     // restore usual image
 	[self setImage:_usualImage];