I would like to delete the "Window Buttons" from the panel.. there is no option to do such thing. What can I do?
Here's what I've tried: Panel -> Add New Items... -> Window Buttons (switch between open windows using buttons)
You have to do this in Settings > Panel. Remove or Add objects in the "objects" tab.
You have to right-click on the panel, then choose Panel > Panel Preferences..., then change to the Items tab, select the Window Buttons item and click the remove button:
That should do it.