Tree pane has stopped being resizeable

[BrianOnHayling]

Hello XYplorers
I used to be able to change the width of the tree pane by the usual hover-until-arrow-appeared, then left click and drag. A few days ago it stopped doing that. I can still do it with the dual-pane display to change the width of each of the two panes. I can resize the width of the data-columns in the file-list pane.
I've searched through the Help docs and found refs to "LockTree" but not found a menu item that will help. I've scoured the WWWeb and found descriptions of the problem, but the solutions refer to some things that I can't find in my installation. There's reference to the configuration file, but when I searched that for "LockLayout" it showed "not found"!
Please help - it's a feature that I'm in the habit of using frequently (I have some pretty broad tree-branches in places!)

[admin]

It worked with 28.30.0700 and then it stopped working with the same version?

[Horst]

Not confirmed
Works fine here with dual pane.
I can resize the tree pane without problems.

[BrianOnHayling]

It worked with 28.30.0700 and then it stopped working with the same version?

I don't remember when it happened. I've recently bought a new laptop and installed 18 programs. One was XYplorer. I was using it on the old laptop to facilitate the change-over, so it's not clear whether or not I ever had resizable tree-pane on the new one.
Is there an option to disable the resizing?

[admin]

Nope, it always works.