Hi i73. That playground uses a fullscreen gui, so you cannot place a control above the fullscreen canvas. There’s nothing up there to place it upon.
You COULD make your drop-down panel-o-GUI… be on a plane (not full screen). Perhaps parent the plane to the cam, position it high, and at display-time, lower the plane into cam-view… perfect.
Did you know controls can be zero-height? Does that give you an idea how to “fake” the drop-down panel? Make it LOOK LIKE its dropping-down, when it is actually increasing height, maybe with a little increasing .top, too?
Let’s take a test drive: https://www.babylonjs-playground.com/#I7LKJY#10
Click on screen, to lower/raise the goo. Fun! Not sure if that will work for your project, but what the heck… it had to be tested. Stay tuned… possible better answers (and possibly better anim methods for control .height) ahead.
You might want to make a custom button class… that installs a raiser and dropper on each button you make (in case you need MANY). Each button might have its own timer… for how long to show it before raising. intelligent buttons… fortified with extra i73 vitamins. EACH ONE could be on its own plane. Wow. When each button has its own plane, all sorts of button-effects are possible.
Fades-ins and dissolve-outs, too. Or just make a particle explosion for entry/exit. You know you have it… when players play-with the GUI… more than they use the actual app.