Limit behaviour of Sizing handle of the comment/reply area

The sizing handle of comments and replies, either in the Annotations area, either in sticky notes, has some issues that could be tackled:

• It allows the reply area to be so short that it hides text. While in a sticky note it then has a specific scroll bar, in the annotations area the text is simply inaccessible unless the size is readjusted
• It allows the reply area to be lengthened outside of the annotation
• If a sticky note is hidden and then shown again, the reply area is reverted to its original size