Thanks. It took me a while to try it live. What you say works as advertised, up to a point.
But I find that in Chrome, in a large multiline text area (e.g., the "body" area in my ISP's web-mail interface), several things happen:
1. It immediately brings up the keyboard, and zooms and scrolls to fill all available screen area with the text area (illogically, it does so far more aggressively than it does with short text fields), often causing the indicators to become disconnected with the ends of the selected text.
2. If I squeeze down the screen so that I can see the entire text area, attempting to move an indicator will cause it to zoom back in, again frequently disconnecting the indicators with the ends of the selected text.
3. Moving the indicators to the boundaries of the text area doesn't autoscroll the text area, and attempting to scroll manually frequently either causes them to become disconnected with the ends of the selection, or loses the selection either
4. If the indicators have become disconnected, attempting to drag them frequently drags the selection instead, or loses the selection entirely.
5. If I dismiss the keyboard, I haven't found a way to get it back without losing the selection, or to delete the selection without it.
6. If I "Select All," I don't get indicators.
Where I come from, it is considered proper netiquette to (unless making a point-by-point response) always put quoted text above the response, and to always trim it to the absolute minimum needed to give the response context. Indeed, the latter is considered mandatory on one of the list servers of which I am a member, and members are frequently set to NOPOST for excessive quoting.
Unless I can precisely select and delete fairly sizable amounts of text, adherence to this standard is effectively impossible.