Fix tab targeting invisible children when switching to the marker deletion prompt

[macbrayne]

Current behaviour:

1. <Tab> until delete icon
2. <Enter>
3. <Tab> seems to do nothing
4. After all invisible elements have been targeted the visible ones are targeted

New behaviour:

1. <Tab> until delete icon
2. <Enter>
3. <Tab> works like expected

[macbrayne]

Hmm, now I remember why I even used that setFocused() overwrite: Without it clicking on the world map tab or the settings tab and then returning to the markers tab would keep the modal open...

Another way of solving the marker deletion prompt being dismissible without interaction would be by not letting it loose focus by tabbing. Currently there still is a "ghost" entry (not present in the other menus!) which removes focus from the modal... However even navigating to the tabbed menu should probably not close the modal which it would even after removing that ghost entry.