With this tool only adjoining walls can be trimmed. Firstly move the cursor to the wall to be lengthened or shortened and activate the function with a left mouse click as soon as the wall is outlined in green. Next select the second wall, again by positioning the cursor over it. As soon as a second wall is detected the length of the first wall is shown in the preview, and thus signalises that the process can be completed with a left mouse click. The tool remains active until it is terminated with ESC, so that several walls can be processed in succession.