vtk opened the ticket and wrote:

This is an issue I've just noticed for the first time after downloading 1.5.0 beta 2. I usually use the right mouse button to scroll in the game, and I usually run the game in windowed mode.

What I expect:
Depress right mouse button; cursor stays in the same spot on the screen, I can move the viewport endlessly; on mouseup, cursor remains where it was on mousedown.

What actually happens (at least 75% of the time):
Depress right mouse button; cursor stays in the same spot on the screen, but viewport movement is limited to the edges of the screen relative to mousedown position; on mouseup, cursor jumps to new position, which is where it would have been after mouse movement had I not used right button at all.

(Windows XP SP3, 32-bit)

Reported version: 1.5.0-beta2
Operating system: Windows

This issue was imported from FlySpray: https://bugs.openttd.org/task/6243