TaskWindow "some command" -quit fails to quit if command crashes

I have written a BASIC program that that launches with the help Wimp_StartTask a conversion tool in a task window when you drop a file onto its main window. The command passed to Wimp_StartTask is in the form:
TaskWindow “conversion command” -task &mainid -txt &01010101 -quit
which works fine as a way to start an invisible taskwindow which performs the conversion in the background and closes automatically when the job is finished.

When multiple files are dropped on the application I just wait till for the subtask (identified by the task id returned by Wimp_StartTask) to cease to exists before starting the next conversion. During a conversion batch, I noticed at one time that conversions stopped occurring because of a taskwindow that remained in the background. When I performed the conversion by hand, the conversion crashed with an “Abort of data transfer”. I killed the pending taskwindow and conversions resumed till another similar case occurred, hence my conclusion that the “-quit” option doesn’t work if the command executed by the taskwindow crashes.

On that note I have been thinking instead chaining the conversions in a permanent, visible taskwindow so that I can see the conversion problems, kind like !Make (chaining compilation of each files in the project) but I don’t see how it works. Does anyone have some kind of example at hand?

Some additional issues:

• I had to define system variables to store the input and output filnames and use these variables in the command instead of the filenames themselves to shorten the length of the command, otherwise if the filenames are a bit too long you endup with “Buffer overflow” errors or corruption in the workspace of other modules. Dunno if the issue comes from the SWI Wimp_StartTask or the TaskWindow command.
• the -task and -txt options are not listed by *help TaskWindow.

On that note I have been thinking instead chaining the conversions in a permanent, visible taskwindow

Can you get your converter to output a character regularly (like the typical \|/- “spinner”) to show it’s still running – you’ll get regular TW_Output messages. If some time goes past with no output (whilst you’ve still had nulls yourself), you can assume it has died.

Command line limitations are one of the things the DDEUtils module addresses, IIRC. There’s no excuse beyond “won’t someone think of the poor Basic programs” I suspect.

Yeah, -task and -txt are not mentioned by *Help because they’re an internal programming interface, and certainly not a user command-line option.