I have an InkScape svg file with some black shapes on a white background.

I need to save this as a PNG file... with white objects... on a transparent background.

I can't for the life of me figure that out.

Help!

make the objects white, switch to Outline view so you can see them. Select them all and use Export to bitmap function. Inkscape's default background color is fully transparent, although the screen looks white.

I'll try that.

I didn't know I had to do "export" instead of "save as png".

(Still not sure why.)

I thought "export to bitmap" would give me a bmp file... not the png file that I needed.

Yes it's a bit confusing to use "bitmap", but this is the "correct" way to get a png. Using Save as Cairo doesn't work as expected with transparency.

There are plans to change exporting and saving in the following versions.