Reproduce:
1) Rightclick HUD attachment
2) Choose edit
3) Try to move the attachment with each of the two movement handles
4) Only one half of each handle is grabbable, the other half is not
Makes it hard to move a HUD attachment around when it is on the right screen border, for example, cause you cant grab the visible part of the handle. You then need to zoom out the HUD frame first and grab the left half of the arrow to be able to move the HUD attachment.
This got fixed in the LL client some time ago, you just need to grab the code there.