Made 'select-tweak-grab' work in 3d window, fcurve and nodes. For nodes it works with both left/right, the others follow user preset for select. Tweak is a WM event, which also follows user preset for tablet-style tweaks (release = apply). You enable tweak events with an operator WM_OT_tweak_gesture. Keymap entries can assign to left/middle/right button or to action/select button tweaks.