System.Windows.Forms.GroupBox hide frame

There is not (short of custom painting code). I think a Panel be better control to use here, although you don't get the text header (just add a label if you need one).

A Panel is probably a better option, but if you really need a GroupBox for some reason, you can modify the code here to create a subclass which doesn't paint the border at all. Specifically, you'll want to override the OnPaint method.

As far as I know this is not possible.

Try using a panel instead.

You could put a label at the top if you want and they practically do the same thing.