btw, pygubu-designer ROCKZ! 👍

Keep the collapsed states of the treeview hierarchy

The collapsing states are not persistent, what they should be, or at least it can be turned on/off via an option.
This is worth one "collapsed" attribute in the data xml structure and would be so helpful. ;)
Right now, the full tree is entirely unfold on every repaint of the preview. With large trees, this is really a bit annoying.

Additional menu entries for

Fold/Unfold children elements for selected element in treeview.
A really good solution would be to integrate a function for toggling the collapsed state (for all child elements) when holding shift-key while left mouse clicking on a treeview element.

Element ordering

Enable dragging for repositioning the elements in the treeview.

Designer binding for testing runtime

It would be also handy (if not still implemented) to can open other windows (toplevel widgets) via a button click, during the testing runtime. Optionally as new instance or a dialog which is block the access to the main window.

ScrollbarHelper

ScrollbarHelper should support adding a frame as a child element. Which is sadly not possible right now.

Thank you, folkz.