If just the condition is disabled:
<img src="https://dl.dropbox.com/u/8367729/construct/pics/toggleDisabled1.png" border="0" />
If the whole event is disabled:
<img src="https://dl.dropbox.com/u/8367729/construct/pics/toggleDisabled2.png" border="0" />
If it's a sub-event and the whole block is disabled you have to right click on the first event.
<img src="https://dl.dropbox.com/u/8367729/construct/pics/toggleDisabled3.png" border="0" />
The condition and event can both be disabled at the same time so you may have to toggle disable on both the event and the condition.