If you made an error while draging&dropping tiles over the wall (creating multiple strips), and you want to get rid of the last strip, do not UNDO ( Ctrl + Z ), because just in this case the correct operation is to click the button you see in the following image (the one with the red square around it, tool tipped with Delete last strip in the Application). In fact, as you learnt in the article called Tile all walls with a single tile (solid pattern, strip by strip) , you are creating a dynamic panel on that wall; by using this button you can remove the last strip you placed on that panel/wall
This article is valid for DomuS3D® 2017 and later versions