There is a problem if you set the selection as follows (as in the video). Then the selection of cells will not be a rectangle.
![318502276-574483c8-34f3-439c-bd98-780142dabc80](https://discuss.prosemirror.net/uploads/secondsite/original/2X/1/126ec099d343199ca8ff86bd70f18ac3ab72c8ae.gif)
This is due to the fact that cell allocation does not take into account the rowspan and colspan cell attributes.
I created a issue here