TEXTURE PREVIEW option that stays while brushing

When you adjust the textures, you get a preview of it over the whole map. It would be super helpful to be able to have a preview option while we brush, so we don't have to either brush over what we didn't want, or to keep adjusting the texture minutely to see the preview.

The image shows the rock texture I placed and the preview texture of the roots I want to brush on top.

1. The texture I wanted to place.

2. The part I didn't want, but got because I can't see where that part is. (the only solution is to brush over it or undo and try again.

The preview for this would be best if the opacity of the preview is adjustable and if it can be a toggle-able option to go back to the original preview that only shows with adjustment.