There are two selection tools. The most commonly used is Select; simply click and drag around the area in the warp, tie-up or weft section to select. After selecting, there are various options such as copy and cut to work with the selected threads.
Select Special allows you to click and drag to select; when the mouse is released, a box pops up with some options as shown below allowing you to extend the selected rectangle through the end thread, through a selected thread, or select all threads. This option is especially useful when selecting more warp or weft threads than can be seen on the design window without scrolling.
When a selection tool is used, the cursor location at the upper right changes to dynamically show the number of threads selected. In the example below, the cursor is hovering over the 17th warp end at shaft 6, and there are 13 warp ends inside the selection box (Threads 13 | 17,6).
When selecting, any scrolling will deselect the selected rectangle. Use select special if you need to select a rectangle larger than is easy to capture and put in the "through" thread.