It is noticed that Robot.waitForIdle() takes unnecessary long time(around 10 seconds) when we call it after calling 'robot.mousePress(InputEvent.BUTTON3_DOWN_MASK)'.
And it is noticed only with BUTTON3(which is a PopupEventTrigger) press using robot and for other buttons it is just taking some milliseconds time only. I have attached a simple reproducer for this.

This is currently noticed only in MacOS x64 platform. I have checked it in Windows x64 and MacOS x64 platforms. I will check and update about other platforms soon.

This is reproducible in 11,17, 20 and 21 JDK releases, but not reproducible in JDK 8.