Changing the label of a panel

Hi I just encountered following problem:
I have several panels and it was alway perfectly fine to change the label but since yesterday I cannot do it anymore. When going with the mouse pointer over the pen sign it doesn’t change to a pointing finger, meaning it is no link anymore.
How can this happen, is there a way to fix the lable so it cannot be edited anymore?

TIA for your answers.

and additonally I want to ask, what to do so the dropdown to select wether the panel is a tab or not can be seen.