Finally fixed bug where kmail lose config.

It's not a bug in template not in kconfig not in ....
It's tab which uses kcfg, widget is not updated to config before we show tab (call a showevent)
So if we show just a tab (for example account change a item and save we will save status
from widget not updated => config will not good)

Perhaps it's a bug in kcfg but this workaround will fix all pb with template/editor config