For me , it's ok to have the Timeline docked at the bottom most of the time , but I can see why some people might prefer to have the Timeline docked at the top, so it is always visible , but out of the way of drawing on the lower portion of the Cintiq screen. Besides , this has been an item supposedly on the "To-Do List" since 2013 ( 8 years !) . Is it that difficult to do ? I can't think why it would be , but I'm not a programmer , so I don't really know.
What I have done in the past is to use the keyboard shortcut 0 to hide the Timeline, but now I use the new Interface: Close/Restore L+R Drawers and Timeline keyboard shortcut in TVPaint 11.5.1 , but I can get it back instantly with one keystroke. (or if I only want to hide the Timeline , still use the 0 key shortcut to hide only the Timeline).