Well alright, let's start with something basic then.
Make a object called 'oButton'
The sprite should have 2 frames, on and off.
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Create Event:image_speed = 0;
io = 0;
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Collision with Bullet event:if io = 0 { image_index = 1; io = 1; }
else if io = 1 { image_index = 0; io = 0; }
with(other){ instance_destroy(); }
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There you have it, one shootable button.