Firefox menu bar bug with global menu applet

To make it easier to spot the bug I used adementary-theme but it happens with every theme.

Screenshot_from_2019-06-16_14_47_00

Screenshot_from_2019-06-16_14_48_14

Screenshot_from_2019-06-16_14_47_17

The first picture and last show the menu bar gap within Firefox when the global menu is active. The second picture shows the CSD mode of Firefox with the global menu active.

Bug occurs in MATE and Budgie from what I saw.