Can't interact with widget while im clicking the mouse button

Hi, im creating a type of keyboard to test some usabilities but im facing a problem.

I created a button that once clicked it opens another 3 buttons. I would like to hover over those 3 buttons and if i release the button while hovered that button will be selected.

Someone knows how to interact like this?

The video shows what i want to do (flicked keyboard) and the image shows how i summoned the second widget.

I appreciate the help!