I meet some problem when I try to put and edit items into a tab page while editing with environment below:
language: C#
editor : Visual studio 17.9.7
MS.net framework : V4.8.09032

1. When I try to drag a item into the tab page from the toolbox, it blocks the action and shows error message “system.nullreferenceexception ‘object reference not set to an instance of an object.‘”, but I can add item by clicking the item in the toolbox and locate the item in the tab page.

2. I can’t move the item I put in the Tab page, when I try to drag it to a the position and released, it will return to its original position in the tab page, But I can resize the item.

is there any setting I need to modified ?

move the item in the tab page while editing