Problems with "Drag and Drop"

Hello,

I'll start by writing what I want to do with drag and drop.

I give a table of value pairs (x|y) and next to it an initially empty coordinate system. Next to each pair of values in the table there is a small marker (small image), which has to be moved with the mouse to the right place in the coordinate system.

The problem is that the mark and the drop zones must be as small as possible, so that an inaccurate drop is not called correct. The smallest drop zone is 24 x 24, and that is too large.

Now I thought the problem could be fixed if I increased the task size of the background image. That also seems to work at first glance. Drop zone and marker are tiny. When I click on them once, it also shows a size of 5 x 5. But on the second click, the size jumps back to 24 x 24 and I have accomplished nothing at all. It still looks exactly the same as before the increase.

The video under 

https://oszlisemeitner-my.sharepoint.com/:v:/g/personal/ba_osz-lise-meit...

shows that nothing changes when you go from 1000 x 1000 to 3000 x 3000 with the task size.

Thanks

Ralph