Say you submit a form in the Manipulation Panel and you get an error which shows a Modal over the top of the Dashboard, including the Manipulation Panel. You close the Modal to resubmit the form and the Canvas unblurs because you've closed a Frame. But, because the Manipulation Panel is still open, we don't actually want the Canvas to unblur in this situation. We want the Modal to know if there is another Frame open and alter the Canvas blur state accordingly.
Say you submit a form in the Manipulation Panel and you get an error which shows a Modal over the top of the Dashboard, including the Manipulation Panel. You close the Modal to resubmit the form and the Canvas unblurs because you've closed a Frame. But, because the Manipulation Panel is still open, we don't actually want the Canvas to unblur in this situation. We want the Modal to know if there is another Frame open and alter the Canvas blur state accordingly.