mouse buttons: middle button should pan, right button should popup menus

[Celada]

It is standard behaviour in almost every GUI application that the button that pops up a contextual menu is the right button, but JOSM uses the middle button for this purpose.

Similarly, it is standard behaviour in applications that support panning by dragging the mouse to use the middle button for this purpose (drag with middle button to scroll the view). Not all applications implement this function but most good applications that deal with a canvas do. Compare with, for example, inkscape, the GIMP, evince, etc... Unfortunately, JOSM uses the right button for this purpose. (Note that web based applications such as slippy maps break this rule and use the left button instead but I assume this is because the standard behaviour is impossible to achieve in web browsers and not an excuse to break the rule in non-web-based applications.

In order words, JOSM has the middle and right buttons backwards.

I consider that it is important to align mouse button commands with other applications. The backwards buttons are seriously confusing to me and make it very difficult to use JOSM.

I did not find any preference setting to swap the two buttons.

[amenk]

The right button can still be used for popupmenus (click and release) even if it is used for panning (click and drag).

If we switch the buttons, people without a middle button cannot use JOSM anymore.