Shift-"Move atoms" eventually becomes zoom

[tmckeith@…]

As a followup to #16705:

"By the way, there’s an odd bug that shows up when I try to rotate groups of atoms within a model using the shift key with “Move atoms” in the “Right Mouse” panel. It works initially when ChimeraX is opened but after a while shift-“Move atoms” acts as Zoom rather than rotating atoms. I haven’t found a way to revert it other than restarting the program. I haven’t entirely figured out what causes the shift, but it seems to happen if I run Isolde or apparently if I use shift with some other “right mouse” icons. I’m using a Macbook Pro with OSX 14.6."

[Eric Pettersen]

Reported by Tim McKeith

[Tom Goddard]

Does the "Move atoms" mouse mode continue to translate (with no shift key held down)? In other words, is only the rotation mode when you hold the shift key broken? If that is the case then my guess would be that ISOLDE or some other tool explicitly assigned shift-right mouse button to Zoom. The shift key is just a modifier of the "Move atoms", meaning if you press right mouse, and after that press the Shift key then it will change to the rotation mode. But if you press the Shift key and then press right mouse it will instead use the shift-right mouse mode assignment if there is one. Normally that is not assigned by ISOLDE may have assigned it. You can see what the mouse button and key assignments are by typing the command "mouse".

I installed ISOLDE in ChimeraX 1.9 and tried the cryoEM tutorial. After the map is associated the "mouse" command shows that "shift right" mouse is assigned to "clipper zoom". That is why shift-right with the "Move atom" mode assigned to the right mouse button is not working because "clipper zoom" has overridden it. You can use the command "mouse shift right none" to unassign shift-right. Of course you will lose "clipper zoom" in that case. Alternatively leave the assignment and to rotate in "Move atoms" mouse mode first press down right-mouse and after that press the shift key. Or if you want "clipper zoom" first press the shift key and then press down right-mouse.

I realize this is a nightmare. The standard solution has been that no built-in tools in ChimeraX explicitly assign "shift right mouse" and instead they only use "shift" as a modifier for mouse modes that are assigned to a button without shift. But ISOLDE does not follow this rule because it wants to assign a lot of different mouse modes.

Here are the standard mouse assignments in ChimeraX

left: rotate
control left: select
control,shift left: select add
control,alt left: select subtract
middle: translate
right: translate
wheel: zoom
pause: identify object

and here are the assignments after starting ISOLDE and associating a map (using Clipper)

control left: select
control,shift left: select add
control,alt left: select subtract
left: clipper rotate
middle: translate
control middle: clipper z shift
right: translate
shift right: clipper zoom
wheel: clipper zoom
shift wheel: clipper clip adjust
control wheel: clipper contour select
alt wheel: clipper contour adjust
pause: identify object

[Tom Goddard]

If you have any suggestions to improve the handling of the mouse button overloading we are listening.