If you launch your project as an "FDT AS3 Application", you get a wonderfully detailed launch screen. In it there's a "start" tab where you can pick what URI you want to load and with what viewer you want it to open. The list includes the internal SWF viewer, the external SWF viewer, the Adobe flash player and the browser. This is great. It looks like this: http://grabs.epologee.com/fdt_start_pane.png
However if you launch your project as an "FDT Flash IDE" task, you don't get that "start" tab. Instead, you get a "miscellaneous" tab that has a very stripped down selection of the one described above. This makes the whole FDT Flash IDE feature somewhat less useful. For example, you cannot use the wonderful External SWF Viewer, and neither can you supply a URI (for example http://localhost/main.swf) but only local files are supported through the OSX file dialog.
Now here's the actual request for improvement: Couldn't the start tab from the FDT AS3 Application task be copied to the FDT Flash IDE launch settings?