Both Word and Excel have an extend selection mode. This works as follows: position the text insertion point somewhere in the document (or select a cell), turn on extend selection mode, click at another point in the document, turn off extend selection mode. Everything between the first and last locations is selected. This is a useful feature if you have only one hand or if you need to select a very long section of the document. (Actually, in Word you can type a character to extend the selection to the next occurrence of that character; for example, F8, ., Esc will extend the selection to the end of the current sentence).
However, Word and Excel enable this feature in different ways, and I can’t think why they shouldn’t be the same.
In Excel you must press F8 to toggle this mode on and off. An EXT indicator appears in the status bar, but is for display only.
In Word, the easiest way to toggle this mode on and off is to double-click the EXT area in the status bar (which is grey when extend selection mode is inactive and black when it is active). You can press F8 to enter extend selection mode, but not to get out of it again (although Esc works for this!
I think that both packages should combine Word’s status bar clicking with Excel’s use of the F8 key.