What is the correct way for me as a noob to contribute with patches for a bugs? Any way, here is a patch that solves the issue

@Tobias Johansson (barfot) please make a diff here https://developer.blender.org/differential/query/all/ leaving the reviewers empty and post the link to it here

Thanks @Aaron Carlisle (Blendify)
My patch: https://developer.blender.org/D1303

I do not remember whether this is wanted behavior or not, Joshua?

Although I can see how the graph editor not obeying this setting could be problematic, several potential issues do need to be pointed out:

• In the Graph Editor, the current frame is used for certain transform operations (e.g. scale, rotate) when set to use the "2d cursor" as the pivot point for those transforms. Not being able to set the current frame before 0 in those cases would be problematic for those cases. Granted, this is probably not used that much, so it may enough to warrant keeping the current behaviour.

• Another use case that may be more problematic is for Driver FCurves. In that case, the user may want to set or snap the cursor to specific values so that the Driver FCurve can be modified or inspected with precision.

The cases pointed out here may turn out to be quite rare, in which case, requiring the user to enable the "use negative frames" option to do this is probably not a bad thing. On the other hand, the fact that this behaviour does cause some visible confusion when the behaviour don't match up between the different editors is perhaps a bigger issue, since we know that this is bound to happen.

I think similar arguments could be made for other editors where it is also convenient to go to negative frames to inspect or modify something. That's kind of why the setting exists in the first place. I would go for consistency and make the graph editor obey this setting.

Thank you all