Possibility to add items to all containers in the layout

Issue #1084 new
Lukas Meindl
created an issue

Currently it is impossible to add items via a layout to many containers such as comboboxes, listboxes etc. This needs to be fixed for the 1.0 Release by allowing to create them (maybe similar to DefaultWindows?) and adding a respective addChild override for the container as is done for TabControl etc.