This report is a dup of bug #184039 and bug #220481, both of which are reported against KDE 4 and I can't change the version to 5.

When enabling "Mouse Click Emulation" in "Touchpad Settings" KCM, the tap detection is set to:
 * One finger: Left button
 * Two fingers: Right button
 * Three fingers: Middle button
On my system - Dell Precision 5520 - the button selectors are disabled so there is no way to choose something else.

If we then set "Left handed" under "Button Order" in the "Mouse Controls" KCM, the one finger taps starts issuing RMB events while two finger taps issue LMB events - which makes sense when looking at the "Mouse Click Emulation" setting but is otherwise very confusing and not very helpful at all.

The "Mouse Click Emulation" setting should be about "primary button" and "secondary button" and setting "left handed" mode in the (otherwise unreleated) mouse setting should not affect that.