textbox1.SetFocus vbmodal?

I would like to setfocus to a textbox but make sure that the user cant press anywhere else but on the textbox. And only if he clicks enter leaves the textbox.
Textbox is on a grid and the user should change the text but not be able to click the grid (because then the grd_clickevent happens) and open another textbox before closing the open one.
Thanks in advance
Brian

After each click on the Form, grid or other controls, perform a test if the textbox is visible ; if so, call "Beep()" and do nothing.
Otherwise, disable all those controls and after the input, enable them again.