System Information
Operating system: Ubuntu Linux (18.04 LTS)
Graphics card: GeForce MX150/PCIe/SSE2

Blender Version
Broken: bed8ad6f95a

Short description
In GPencil, multiframe editing seems to always take the current frame as a reference for all manipulations. In most cases it doesn't make a difference or is just what I want. But there is at least one operator where it would be useful to actually go through each frame of the animation while it is being calculated: Reproject with surface setting.

To reproduce:
Base file:

select Stroke object, switch to edit mode and make sure multiframe is active and current view is camera. Select all GP keyframes, then all strokes. (should be already set up like this) In the menu, choose Strokes->Transform->Reproject->Surface.
Expected result: Stroke is positioned on the moving plane for every selected GP keyframe.
Actual result: Stroke stays in one position based on whatever the current frame was when running the reproject operator.

Suggestion
Maybe this could be a sub-setting for the multiframe mode. Something like "respect animation".