How to divide a pane to 12 or more equally when the size of the pane is changed automatically? What widget can be used?
You could put 12 panes into your pane. You might be able to get the size change you want automatically using Anchors. Otherwise you need a callback on your pane in which you adjust everything. I think the Anchors will be useful if you just want everything to stretch in place. If you want to re-arrange things in a more complicated way, the way a browser does with HTML then you will need to do some work in a callback.