client: made indicator for open imports show up immediatly The indicator in the main menu button relies on the staged imports to be loaded, which formerly only happended when opening the respective staging area box. Now they are loaded in the mounted hook of the sidebar component. Maybe this kind of calls should be made in a more central place.

teichmann@intevation.de = sascha.teichmann@intevation.de
bernhard.reiter@intevation.de = bernhard@intevation.de