Need help with polling keyframe transformations

Hi i made this little addon: https://github.com/Ulf3000/Blender-Timing-Tools

it provides ripple editing (all later keyframes move too) for normal keyframes and gp right now , but i plan to add a few other functions later. ive been using it for a while and it proved usefull.

my operators work when i bind them to shortcuts but especially for ripple editing i´d also like to implement the function for the user mouse dragging a keyframe or using g.

for that i need to poll that. but i have no idea… maybe you guys could take a look.

thanx alot