How to revert a subfolder back to general project properties

[Peeters.Bram]

I changed the properties of a subfolder (causing it to get a wrench icon), and now I want to undo that but I cannot find a way. There is a restore defaults button which i tried but the wrench button is still there do i am guessing this means the folder properties will still not be in sync with the general project ones. Any other clean solutions ? If not I hope editing the the project file directly (which is apparently a bit of an undocumented mess) will do the trick ?

[Peeters.Bram]

After trying a bit to see how the folder specific properties change the project file it seems there is a <folderInfo .... > entry created for these special folders. If you delete the entry for your folder from the project file you can get it back in line with the general project properties (the restore defaults button just changes things inside the <folderInfo ...> structure but it does not remove it). So I can continue working but I am still interested in a clean way to do this via the gui though .