Drawing: don't merge with neibghouring objects

[jtagcat]

Current	Desired

[slymz]

E.g. two simple boxes can not be drawn side-by-side:

    want            have
┌────┐┌────┐      ┌───┬┬───┐
│    ││    │      │   ││   │ 
└────┘└────┘      └───┴┴───┘