Cannot resize GUI panels under v15.0.1

[rjmoses]

I installed QT Creator GUI 15.0.1 along side of v4.14.1

The GUI panels will not allow me to resize components on 15.0.1.

Example: If I split the Left Sidebar to show Projects and Bookmarks, I cannot change the size of the Bookmarks on 15.0.1, but it can be changed on 4.14.1

As an isolation test, I did a clean install on a Virtualbox system of QtCreator v15.0.1 and I can resize components.

I have looked at the settings on both v4.14.1, the Virtualbox system and v15.0.1 and cnnat see any differences (but I am a novice at the internals of QtCreator.)

Any help or thoughts will be greatly appreciated.