I notice that (successful) region file uploads produce an entry in the layer dialog of the form "REGION_PLOT_TYPE-(serial number)" (e.g., "REGION_PLOT_TYPE-7"). It would be helpful to the user if the filename of the uploaded file were retained and displayed in the layer dialog.

Since regions can be created by API, not just by file upload, the file name convention can't apply in all cases, so the "serial number" approach may still be appropriate for API uploads. However, even in that case, I think a more user-friendly string than "REGION_PLOT_TYPE" would be an improvement. Does the API allow regions to be given names that could then be shown in the layer dialog?

TODO in this ticket:

• use the file name as label in the layer dialog. In cases that the file name is too long, treat it the same way as uploading an image, use only the characters fit in proper length space, and display the full name as tooltip when mouse over it.
• make sure it behaves the same in API, providing a label field for caller to set the label for display.  If there is no label supplied, use string "ds9 region overlay-{N}". N will start at 1, and increase by sequence as it does now. 

Also implemented: 

• File upload pane is also updated to show the long file name of the uploaded file in shorter style as that shown in the layer dialog.