causes components to move out of position. See post in Help “Select components in container”
It looks like this may be a bug in the Designer, thanks for reporting it. I’ll make a ticket for it.
As a work-around, you might try grouping your items before moving them into a container. I know it’s a little backwards, but it seems to work for now.
I have also seen this recently. Grouped a series of lines spaced horizontally inside a container. When I did, it moved several (not all) of the lines on top of one another.
This has been fixed for 7.3.5