This action checks for the initial down press on a mouse button. It will return true on the single game tick that the mouse button is pressed down and false at all other times. If you enable the not modifier, this action will be reversed, and check if the mouse button has not been pressed down, returning false on the game tick that it has been pressed down and true at all other times.
Note that to add actions into the "if" block, they should be dropped to the side of the action, as shown in the image below:
These actions will now be run if the "if" evaluates to true, while any actions dropped elsewhere will be performed after the "if" block.
Argument Description Mouse Button The name of the mouse button to check (left, middle, right). Not Negate the check (true becomes false and vice versa)
The above action block code polls the mouse button state every step and if it is being held down it checks for the initial mouse down press. If the check is on the initial down press, then a sound is played, then while the button is down, the sprite blending is changed to red. If the mouse is not being held down, a check is done on the mouse release to reset the blending colour to white.