Steps to reproduce:
01. Start a new Android GUI project
02. Add 2 jButtons
03. Position them as shown on the first pic below
04. Select all the 2 buttons
05. Move them by using mouse
06. You will see it gives you weird result
07. In some rare cases it can crash the IDE
Tested on Lazarus 1.8.0RC5 x86_64 Gtk2 + LAMW 674 on Ubuntu Mate 17.10.