One way that I can think about accomplishing this is to add an if statement to the button's activation. If you can save the "mode" inside a variable, you can put an if statement inside the method that it's calling.
For instance, if the mode paddles were selected, then set the variable to true. If the paddles are pressed, the method should run a check to see if the variable is true (and if it is, run it).
One other way that I can think of is to make two separate windows (one with paddles, one with the key) and when the mode is selected, take the user to that window. This has the benefit of allowing the programmer to prevent the other "control" from existing in each respective window but might be less efficient and bulkier.