Not sure why prasad_N wrote the bit about not being Qt related, I would say it clearly is.

If you just want the button's enable state to follow the checkbox's checked state, then just connect the checkbox to the button
Qt Code: 
  1. connect(checbox, SIGNAL(toggled(bool)), button, SLOT(setEnabled(bool)));
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You can even do this in Designer, using the signal/slot mode.

Cheers,
_