Sorry, I don't have an ans wer to your issue, but from curiosity, I have never seen an ink jet printer print white. It uses the paper white itself.
Maybe there's some insight about type of printer or ink?
Fred

MelW: yes, but then I have to measure and cut the borders I need. I print on a 44" roll and need to lay out multiple prints. I set borders as needed for each print and tell Qimage to print cut marks. After printing I trim down.

When printing with Relative or Perceptual rendering setting the borders as white causes no trouble. The printer does not lay down ink in the borders.
When printing with Absolute rendering the white borders get inked, which is what I don't want. Transparent borders would solve this.

This is all actually a follow on from this thread:
http://ddisoftware.com/tech/qimage-ultimate/transparent-borders-absolute-colorimetric-rendering/

Mel has a great idea, but it's even simpler.  Borders, text, and page background always follow the main color management settings (those defined by "Printer Profile") because they are not technically part of the "print".  So you can just set the main color mgmt settings to relative colorimetric and then select all prints and tell it to render the prints themselves in absolute colorimetric:

(1) Click the tool button to the right of the "Printer Profile" dropdown and set those main settings to relative colorimetric.
(2) Click on a print on the Live View and press Ctrl-A to select all prints.
(3) Right click on any selected print and select "Custom Color Mgmt Settings".
(4) Click the "Custom" radio box at the top and select "Absolute Colorimetric" beneath, then click OK to close the dialog.

By setting the main color management settings (tool button next to "Printer Profile") to relative colorimetric, you are telling QU that you want everything set to relative colorimetric.  Then by doing the above sequence, you are telling it that you want all prints (and only prints) to render in absolute colorimetric.  This should give you what you want.

Note that this request is a bit atypical of what users want to do.  Normally when you print something with white borders, you want the white in the borders to match the white in your prints.  Doing it the way you request, you'll get a border that doesn't match anything in your print (white in the border will not look like white in the prints) and that can throw off the color of the final print(s).  Typically the border will look more blue and make the print look like it has a yellow tint.  And that's true even if there is no white at all in the prints: the relative bluish tint of an RC border on an AC print will tint the whole print a little yellow to the eye.

Mike