How to detect individual collision

[Jan Sælid]

Hi there

I'm trying to make a timeline-bar where you can add or delete rectangles conatinig "whatever". The user is able to move a rectangle left or right, but if it intersects with another rectangle, it will stop....

Because the user is able to delete and add new rectangles I have to make some sort of function check if the moving rectangle is going to collide with other rectangles to the left and right. (like the timeline in Adobe Premiere) I know this is possible, but how do I do it fast..... Checking every rectangle with repeat is to slow.....and the only idea I have now is to make a list in a hidden field-table for every new created rectangle......

any ideas....?