Monitors with different pixel sizes

I have several monitors with different pixel sizes (that is, size of individual pixels; not resolution). This means that when I put them next to each other and move the mouse between them, it's not perfectly smooth.

I know that in Windows, you can move monitors up or down relative to each other; but is there a way to "scale" them? To say "They have the same pixel height, but this one is an inch taller"?

There is no way to do that in the default interface. Some third-party app might do that, but I'm not sure what such a setting would imply. (Would an app's window get resized as you moved it from monitor to monitor?) Maybe we'll get it when we get resolution independent operating systems and window managers.

Unfortunately, the solution right now appears to be to move the monitors to different distances from you so the pixels appear the same size.