Paint Shop Pro comes with a plethora of masks you can save as png files for your layouts. Here's how:

Open a document with transparency and fill it with a color of your choice. I chose black here, and a 12x12 page.

On the toolbar (this is PSP8 but others are similar) choose Layers, Load/Save Mask, Load Mask from Disk. You will find lots of choices to play with.

The drop down menu has your choices. I've selected this one. I've checked or defaulted to Source Luminance, Fit to Layer, Invert Transparency, and Use Image Value. Now click Load.

Your new image looks like this. However, you have several layers, and you just want one.

Go to Layers, Merge, Merge Group. After the merge you will just have one image layer - your edge - with a transparent background.

Suppose you want to change the color. Lock the transparency of your layer.

Now use your fill bucket to add the paint color. Make sure your "Match Mode" is set to "None". With this and the transparencey locked, it only fills the pixels in your edge.

To save your edge - File, Export, PNG optimizer. Select alpha channel transparency as you would when saving any other element with a transparent background.

Tip: You can also File, Export, Picture Frame. Then it will be in your presets whenever you need it.