The only way I've found is a work around which is to open  Photoshop (not Beta) first, minimize it, then use Lightroom Classsic as usual.  This is NOT ideal, but works for me.. ... View more

Sorry, 'Fit' (not 'Fill') will correctly proportion the image but will not fill the window.  (Fat fingers . . .  :-)) ... View more

Thanks, Michael - that's the same ratio I calculated.  However, just for clarification, it does matter in Windows which Picture Position is chosen.  Please try the following settings in Windows 7 to understand what I'm saying:  'Control Panel' - 'Appearance & Personalization' -'Personalization'-'Desktop Background'  Here there are five settings, each which change how an image is displayed; namely, Fill, Fit, Stretch, Tile and Center.  Fill will expand the image beyond the display borders but completely fill the screen.  Fill will correctly proportion the image but will not fill the window.  Stretch will do weird things to the width.  Tile will also do weird things to the image.  Center seems to be my best choice.  I should note that I use two screens to project my images in LR; one is set to Portrait and one is set to Landscape.  Using Center seems to project my image correctly on one of my monitors, depending whether it is Landscape or Portrait. Please, give me your thoughts . . . ... View more

dj_paige - thanks again.  My screen resolution is 1920 x 1200 instead of 1920 x 1080.  Is there a ratio other than 16:9 that I should use?  Here are the steps I use to export for a Windows Desktop background:  1) crop the image in LR to 16:9 using the crop tool, 2) set the resize to fit, long edge @ 1920 pixels.  Here is a screen shot of the preset I saved.  What am I doing incorrectly? ... View more

dj_paige - Thanks for your help.  Actually, I did follow the directions EXACTLY; the issue I had was not with following directions but with the Windows setting.  If you're a Windows user, please try setting your Desktop B ackground setting to FILL and then see what happens to the image when it's displayed as a background.  It will Fill the screen, but the resulting image will be expanded so that much of the image will exceed the screen's margins.  Changing the export setting to 1920 pixels on the long edge changes the size of the image, but doesn't override the Windows desktop background setting.  It will still try to expand the image to fill the entire screen. ... View more

Also, I found that, while a ration of 16:9 correctly matches the 1920 x 1200 screen size, it is not always necessary to crop your image to that ratio to show acceptably as a wall paper.  I tried with various crop ratios and found that the wall paper displayed (for me, anyway) acceptably for most crop sizes.  The resulting screen background will not completely fill the screen, but it seems to display the image very close to what I see in LR. ... View more

dj_paige - my setting was set to "FILL" rather than "FIT".  Thus, Windows tried to fill the entire screen with the image by enlarging the image until it 'fit.'  ... View more

OK, I figured where I went wrong.  On a Windows computer, be sure to set your 'Desktop Background', 'Picture Position' setting to "FIT."  The resulting image will be somewhat smaller for a vertical orientation but will show the image correctly as a wallpaper. ... View more

Well, I also tried this method and found that it didn't work for me.  My screen resolution is also 1929 x 1200.  The resulting image using this method comes out much bigger as a wallpaper than the original image.  Any other ideas? ... View more