I recently ran into a problem when using 9 patches: The origin can only be placed top-left or center. If you have a meter or something that you want to shrink from the left to the right, not from the right to the left, but want to use a 9 patch, you may encounter some issues.
If you wanted to achieve this using a Tiled Background, clipping from the left to the right, it can be achieved by setting the width to a negative. This trick doesn't work with the 9 patch because of the way the margins work. If you want to do this, it requires placing the 9 patch on its own layer and then rotating the layer 180 degrees. Then you just invert the image both horizontally and vertically in the image editor. (It doesn't give you the option to rotate 9 patches so you have to do it this way)
Feels kinda dirty doing it this way however, is there any other way to accomplish this? I tried setting negative margins but that doesn't really work and I didn't anticipate it working. Is there a specific reason why they don't let people anchor the origin for 9 patches and tiled backgrounds to user defined positions aside from top-left and center? Any thoughts as to other solutions to this issue?