You are able to place a glass pane where you should not be able to...

If you do the following with normal glass panes it works fine...

If you stand between two COLOURED glass panes, facing the pane at the other site you are able to place a coloured pane right where you are.
You need to lean back just like in the picture.

EDIT:

I tried it out again for both, means coloured and normal glass pane (MC version 1.7.4) and it came out that it now works the same as stained glass panes with normal glass panes...
But blocks doesn't work in one of these two cases...