Noobie question:

I've drawn a rectangle, clicked Fill and Stroke, changed the fill color - no problem.

Next, I chose stroke style, width 3 px, then Stroke paint, and chose black.

So, what happened to my border? It fails to appear?

Please share/upload the file, it may help.

Here's a tutorial I wrote to help people track down this kind of problem (which we see ALL the time). Typically it's because something has been made transparent.

What To Do When A Tool Stops Working (or Tools are Drawing Invisible Objects)

(btw, anyone is welcome to link to the tutorials at IC -- they're there for anyone to use, member or not )

Yep, the alpha slider. Thanks for your tutorial. But may I suggest that the slider have a bigger icon - maybe a handle or directional arrows, so that new users notice it?

You may. But unfortunately, this is not the place where developers will read it. If you can make a mockup of an alternative user interface for the alpha slider and send it to the developers' mailing list, you may start a discussion about this. At LGM in April, they plan to meet up with a few designers to discuss UI issues, and knowing which issue might be relevant would probably help them.