I have discovered a way to fix this easily. Once you work through this tutorial you should be able to apply this method to all your bordered background projects, including all variations, right, left, top, etc.

Here we go.....

Create a new image 1024 wide/100 height/background white/16 million colors. (this is only to give you a working image in order to explain the technique, you can use your own preferences regarding the width and height dimensions, personaly I recommend using at least a width of 1024 or larger).

Pick up a color for your foreground (for this demo I am using red), and using your selection tool, select an area 100x100 in size starting at position 0x0. You should now have a square area in the far left of the image selected. Using the color fill tool (paint bucket), set to solid color, fill the selected area with your foreground color.

Step 3.

Now go to images/effects/drop shadow and use the following settings...
color = black (or a contrasting color to any colors in your image)
opacity = 100
*blur = 0 (note: The blur *MUST* be set to "0". Click here to see why)
vertical offset = 0
horizontal offset = 15

Click 'OK'. Using the magic wand click on the black drop shadow you just created, select JUST the drop shadow area (here is where it paid off to have a color that is HIGH contrast for your drop shadow).

Step 4.

Pick up the color fill tool and change the fill style to linear gradient and click on options in your tool pallet, set the blend mode to normal and the direction to 90 degrees. Click 'OK' and then making sure the foreground color is still black and the background is white, fill the selected area.

You should now have a drop shadow that will tile perfectly without any 'gaps' in it. Click on the image below to see it tiled.  You should now be able to apply this technique to all your borders. Just make sure you always use a color that IS NOT in your image for the drop shadow. This makes the magic wand selection easier and your blur is set to "0". Try different color variations for the linear gradient color fill, match them to your color scheme.

Click on this image to see it as a background.

If you have any questions or comments, feel free to email me at creativegrafix@geocities.com

Special thanks to Sandy Blair for being the inspiration behind this technique.

Like the background on this page? I made it using some of Sandy's simple filters. You can get Sandy's filters at Sandy's Simple Filters Page. 

For more of Sandy's filters along with some other great ones visit PC Resources for Photoshop, the Official Home for the Filter Factory Galleries.

For more tutorials and resources visit the Paint Shop Pro Users Group.