When switching the mouse to left-handed mode (using systemsettings), only Core-Events are changed, not XInput events.

a) This is yields to problems with programs using XInput, e.g. for supporting different input devices. See below for a example program.
b) Solving this issue would be a step towards solving bug 244736 - "Changing mouse buttons order from Systemsetting modifies all input devices settings", as XInput settings can be set for each device.

Expected behavior
==================

Instead of modifying core-event settings, KDE should modify XInput settings. (Until the settings GUI supports selecting the device, as an intermediate solution, XInput settings could be set for all mouse devices.)

Reproducible: Always

Steps to Reproduce:
Steps to Reproduce
==================

1) Preparation: Get the XInput-ID of your mouse

$ xinput list | grep -i pointer
⎡ Virtual core pointer                          id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ HID 046a:0023                             id=9    [slave  pointer  (2)]
⎜   ↳ Microsoft Microsoft USB Wireless Mouse    id=10   [slave  pointer  (2)]

---> spot the id, in this case it is 10

2) Make sure KDE mouse settings is set to right-handed mode (which is the default)
3) Verify expected behavior
3.1) Physically left button is button 1, Physically right button is button 3
   xev | grep -A3 Button
3.2) check xinput button mappings
$ xinput get-button-map 10
1 2 3 4 5 6 7 8 9 10 11 12 13

--> buttons are not switched (as expected)

4) Switch KDE mouse settings to left-handed mode.
5) Check behavior
5.1) Physically right button is button 1, physically left button is button 3 (as expected)
   xev | grep -A3 Button
5.2) check xinput button mappings
$ xinput get-button-map 10
1 2 3 4 5 6 7 8 9 10 11 12 13

--> buttons are still not switched (in XInput)

For proofing, this is a problem, use xournal <http://xournal.sourceforge.net/>.
6) Still in left-handed mode, start xournal
7) Ensure "Options -> Use XInput" (in xournal) is enabled (which is the default)
8) Click on some icons in the toolbar using button 1 (physically right) -> works
9) Try to draw some line in the main area of the window using button 1 (physically right) -> does not work
10) Try to draw some line in the main area of the window using button 3 (physically left) -> works, but is wrong button
11) Now disable "Options -> Use XInput"
11.1) Toolbar elements are still working when clicked by button 1 (physically right) (as expected)
11.2) Drawing is now possible using using button 1 (physically right)

This shows, the misbehavior in xournal is reasoning in KDE not changing XInput but core events.