Docking / Re-Docking active windows

[zaracay]

After un-docking a tool panel, there is no active window selected. If the tool window is clicked, it does not become active. In order to re-dock, I have to click the main Seg3D window (at which instance it becomes the active window) followed by clicking on the floating tools panel (now making it the active window). Only after this action can the window be redocked.

Consequently, the checkerboard window in the upper left corner disappears after the redocking.

Finally, after undocking and redocking several times, I can no longer redock. I was able to get it to work a few times after re-sizing the main window, but even then, it stops working after too many times.

[zaracay]

For the final comment in the original issue. The panel can be redocked after perturbing the panel and trying to redock.

[a-y-khan]

@zaracay can you try again with the Qt 5.9 build I posted to the scirunlunch Slack channel? Qt 5.9 may behave better...

[allywarner]

Behavior is improved, but still has bugs. Undocking button doesn't always respond. To redock you need to click once on the undocked window, even though it's active, and then you can double click to redock. The docking has issues when Seg3D is the size of the entire monitor.