Today, 01:14 AM
Screenshot image is way too small to be usable (better give a full size JPEG than a scaled down small PNG).
If Select > None is disabled there is no active selection, and if it isn't, just used it top remove any unwanted selection.
Remember that you cannot paint the layer (or its mask) outside the layer boundary (but what would be the point of painting the mask outside of the layer)
Looking at the controls it appears to be Gimp v3. The green line is the layer boundary (It is green when the mask is selected, instead of yellow when it is the layer). Clicking on the bottom layer should make it appear (in yellow) around the whole image (boundary of the bottom layer). This is not the selection indicator, which is moving (marching ants).
If Select > None is disabled there is no active selection, and if it isn't, just used it top remove any unwanted selection.
Remember that you cannot paint the layer (or its mask) outside the layer boundary (but what would be the point of painting the mask outside of the layer)
Looking at the controls it appears to be Gimp v3. The green line is the layer boundary (It is green when the mask is selected, instead of yellow when it is the layer). Clicking on the bottom layer should make it appear (in yellow) around the whole image (boundary of the bottom layer). This is not the selection indicator, which is moving (marching ants).