When I leave the Explorer (the little tab on the left side, I don't know the proper name) unpinned the list box is unusable.
When I click on it then move my mouse the window slides away.

It is mearly annoying since you can access the same folders below it without problem but alas I see the box first and immediatly click on it every time.

Is there a setting that I am missing or was set that would fix or cause this.

Thanks

Probably you mean combobox in the Explorer tab. When it is selected and Explorer is unpinned, it may become inactive (wrongly of course) and slide off.
We're aware of this problem and possibly will fix it soon.

Yep that would be the right one.
I thought that a combo box allows you to enter text and not just select it. Guess I better get up to date on my controls.

FYI, problem with combo will be fixed in build 4518.
Stay tuned