This needs to be supported by whatever is rendering the menu and handling events (in this case, Unity). However, I'm not even sure that gtk supports this feature. I think it was a Gecko only feature, so you're probably pretty much out of luck to have that supported again
This needs to be supported by whatever is rendering the menu and handling events (in this case, Unity). However, I'm not even sure that gtk supports this feature. I think it was a Gecko only feature, so you're probably pretty much out of luck to have that supported again