Could not fill because the affected area is empty or does not overlap the canvas.

This may not be an application bug, because when I create a fresh document and use the fill command, it works just fine. It seems to be specific to the file I'm working on, which has a number of locked layers (transparent pixels in layer are locked). When attempting to create a new fill layer at the bottom of the layers panel, I get this error message: "Could not fill because the affected area is empty or does not overlap the canvas." When I unlock these "transparent locked" layers, I can make the fill just fine. So this may be a feature request:

• When selecting a subfolder that contained locked layers of any type, can you add an unlocking function that applies to all the layers in the subfolder?
• If the feature exists already, can you please add it to the layers submenu?
• If this is something that I can toggle on, can you tell me where in General Settings I can do so?