Often a couple of objects are placed side by side, all with the same distance to each other. Except the duplication dialog, LibO has no aids to place controls at the same distance like similar objects. Microsoft Visio calls this feature alignment and spacing guides.
Created attachment 125392 [details]
Spacing and alignment guides in Google Draw
*** Bug 103299 has been marked as a duplicate of this bug. ***
Nice GSoC project...
*** Bug 132848 has been marked as a duplicate of this bug. ***
*** Bug 134409 has been marked as a duplicate of this bug. ***
*** Bug 143236 has been marked as a duplicate of this bug. ***
The placement guides for single objects are available as UNO .uno:HelplinesMove "Helplines While Moving"
But they only toggle active, when an object has been selected and is being dragged with l-mouse click & hold.
If without actually starting to drag an object the help lines could be toggled shown for a selected Draw object
1.) to check its alignment, or
2.) while moving object with <Shift>+<cursor L,R,U,D> (currently no guides with this keyboard only movement).
The other facet is that the current help lines show the 'extents' of the object--not the centroid of the object. Sometimes for positioning working against the center is better than the x,y extent.
Helpines from the centroid of the object, that snap to the center of the document, would indeed very helpful