Why don't non-square images work properly with some filters?

I'm sure this has been covered before, but I haven't been able to locate a previous thread, so please pardon me — I've noticed there are a number of filters (like Zephos' Speedliner and Manga Kata) that don't work properly on non-square images, like landscape ratio ones. When I try to apply them, the filter effect doesn't stretch to include the whole image, and stays square and tiles with a glaring seam.

Is there a way to apply these filters to stretch properly across wide or tall images? Thanx in advance.

It's one of those things personally that has driven me just a wee bit crazy in a few of my filters ^_^ The current version of Speedliner Lv2 should actually now have the ability to extend across a tall or wide images, just use the Extend Mode near the bottom of the controls and it adapt to the image as follows:

Extend Mode 1: Square
Extend Mode 2: Wide
Extend Mode 3: Tall

It was really weird coming up with it, but using ubersev's Proportional Gradient as a corner, it's possible to stretch the effect on quite a few filters. Unfortunately, Manga Kata is still on the first version, so it doesn't have the same technology for the speedline... yet ^_^

Of course, the above being said, having a non-tiling/proportional stretch mode hard coded into the program would be at the very top of my wish list ~^_^~