Optimizing changing app on the fly in subapp

I have a main app from where all other apps loads and is shown in a subapp. The subapp temporarily covers the main app. This works fine. The issue is when switching app in the subapp you can see the main app for a split second.
Anyone have a "pretty" solution to this? Because it doesn't look good having it like this.

Solved it! :)

Used 2 subapps and loaded second app before first closed. No main app shows in between.

\me pats self on back ;)