[Enhancement] Have separator between vertical view panes - v1.6

[jonk999]

Is your feature request related to a problem? Please describe. In V1.6, when you select View, Folder or View, Album, etc the pane that opens doesn't fill the entire vertical space. As such, I thought that not all folders or albums were showing until I noticed the scroll bar.

Describe the solution you'd like Either have a visible separator when only or more one of the view options is selected and the entire vertical pane isn't used. Or have the view use the vertical space available on the pane depending on how many options are selected.

[RupertAvery]

Can you see if this is better?

https://github.com/RupertAvery/DiffusionToolkit/actions/runs/7859182787/artifacts/1236063359

You can now resize the navigation panes.

[jonk999]

I downloaded the version at the link provided and when I run it I get the following error: An unhandled exception occurred. Value cannot be null (Parameter 'element')

When I 'ok' the error the program then closes.

However, it appears to be fixed in the version from https://github.com/RupertAvery/DiffusionToolkit/issues/211 where the entire pane is now filled.

[RupertAvery]

This should now be working better in the latest official version (v1.6.1)

Navigation panes are now resiziable, and the last pane will always take the full height available. Also, Value cannot be null (Parameter 'element') errors should be fixed