Thumb is Always Selected

Because of the way that Drupal is dealing with variables (perhaps this is a core bug), checkboxes with numeric values need to not have a zero because Drupal gets confused between 0 and not selected. Because image.module uses 0 as the id for the thumbnail size, this checkbox is always selected when you go to the image_exact.module settings page. This patch adds "size-" to the beginning of each key, so that things are stored in the variables table as:

    [image_exact_size] => Array
        (
            [size-3] => size-3
            [size-0] => 0
            [size-1] => 0
            [size-2] => 0
        )

instead of:

    [image_exact_size] => Array
        (
            [2] => 2
            [3] => 3
            [0] => 0
            [1] => 0
       )

Then when the variable is called back out, the "size-" is removed. Problem solved.

-jeff