Please make sure that we can rearrange columns in list and trees by dragging the column headers to their new position. For starters, just enable the corresponding support in Vaadin; we might have to adjust the visual design a bit.

Eventually, however, a changed column layout will have to be persisted on a per-view basis and there need to be a way to reset to the default layout - it doesn't make much sense to be able to rearrange columns for one edit session only.