In this GIF, I try to click on the smiley face inside of the TextBox. Now it has it’s own ScreenGui, and is not parented to the TextBox, and the smiley’s ZIndex is 500 for precautionary measures. Basically no events for the mouse will fire while a TextBox is selected, and the action is inside of the TextBox. I believe that this is not intended behavior.
I should also mention that the smiley also does not fire any events for the mouse as well. MouseEnter, MouseMoved, and MouseLeave to name a few.
Edit: mouse.Moved seems to work while a TextBox is focused, just not anything else