In our web application, we have a list of items for which multiple actions can be scheduled. If an action is available but not selected, it is displayed as a gray button. When the user clicks on it, the button changes to a color, indicating that the action is scheduled. When the user clicks on it again, the action is cancelled and the button reverts to its previous state. One such button is displayed for each action, for each item.
My team has raised a couple of concerns:
The gray color may make the user think that the button is disabled
It may not be clear to the user that he can cancel the action by clicking on it again
I don't think this is a problem, especially if we use tooltips (The "vote" and "accept answer" features of StackExchange are implemented the same way), but are there ways to improve the usability of these action buttons?