Make OakKeyEquivalentView opaque

This is a minor performance advantage and prevents mouse-down events from moving the window (when the control is used in a textured window).

Frameworks/OakAppKit/src/OakKeyEquivalentView.mm

@@ -168,6 +168,11 @@ static NSString* const kRecordingPlaceholderString = @"…";
 	return self.showClearButton && [anEvent type] == NSLeftMouseDown && NSMouseInRect([self convertPoint:[anEvent locationInWindow] fromView:nil], _clearButtonRect, [self isFlipped]);
 }
 
+- (BOOL)isOpaque
+{
+	return YES;
+}
+
 - (BOOL)acceptsFirstMouse:(NSEvent*)anEvent
 {
 	return YES;