Some drop-down menus are hard to notice

[Fredlyb]

Godot version:
3.1 stable

Issue description:
Some drop-down menus do not look like menus. The name of the node in the inspector, the "tilemap" at the top of the tilemap bar. Those ones.

After a year using Godot, I just now learn that these can be clicked. This is not properly shown in the design, it is flat and looks like a title, causing much confusion for anyone who doesn't know otherwise.

Other interactive elements in the editor are coloured differently, hinting at their press-able qualities. Just do that for those too. Important tools are hidden behind these invisible drop-downs.
Just like this :

And then no more confusion, everything is clear. Just make it the same as other similar buttons.

[KoBeWi]

Resolved by #48742