Manually sort list with drag&drop or up/down-arrows

Hello,

I am running into a problem that seemed so easy at first but drives me nuts now.

I need to manually sort a list during a live session either with drag&drop (preferred) or choosing an index and sorting with up/down-arrows (second choice).

Example: Moving the 4...

1 2 3 4 5 6 7 8 >> starting point

1 2 3 5 4 67 8 >> move the 4 to the right 1 time

1 2 3 5 6 4 7 8 >> move the 4 to the right 1 time

1 2 3 5 6 7 4 8 >> move the 4 to the right 1 time

1 4 2 3 5 6 7 8 >> move the 4 to the left 5 tims

My Approach was using zl.swap and the incdec object, but my patch makes a mess. Everytime I switch directions, the old target makes another swap, making my patch useless.

Here is my patch:

Anyone did this before or has a hint?