I use a popover has a context menu in Terminix. When a user right clicks the terminal, the popover is shown at the position clicked using gtk_popover_set_pointing_to. 

Under Wayland when the terminal is positioned near the top of the monitor and the window size is smaller then the context menu, the popover gets positioned on the right such that it goes past the top of the screen. My expectation is that the popover would be positioned under the rect specified in gtk_popover_set_pointing_to so that the popover remains completely visible.

Please see https://github.com/gnunn1/terminix/issues/805 for a picture of the issue. I can reproduce it on my system as follows:

1. In Terminix go to Preferences | Appearance and set the "Terminal title bar" option to None to force it to use a larger context menu

2. Drag the Terminix near the top of the screen and then set the height of the window relatively low, say five rows in the terminal

3. Right click the terminal at the top, the popover will be clipped at the top of the monitor.