admin2: Replacing checkboxes with a gridlist for glitches and special world properties

[FileEX]

Recently, new special world properties have appeared, which means that there is no space for new properties (next checkboxes) in the admin panel. I believe that replacing checkboxes with a gridlist is the best solution.

Old list (without enough space for two new properties)

New solution:

To enable or disable a glitch or a special world property, just double-click on a row in the gridlist.

I added two new properties burnedflippedcars and fireballdestruct

[jlillis]

Looks great. Do you think this could be easily back-ported to admin?

[FileEX]

I think we can also back-ported it to admin. Especially since it is not known yet when admin will be replaced by admin2. But admin does not have a tab with glitches and special world properties.