Starting in an earlier version, I had a wall with some vines placed at the top (on stone bricks), which then grew down over a window (of glass blocks). Today with version 1.2.5 I noticed a gap and tried to fix it, and found that I could not place vines on a glass block. (Also, when I broke a vine growing on glass, the vines below it broke as unsupported.)
For all I know, this is an intentional change, but I haven't heard that it is, so I'd like to draw your attention to it in case it is a bug. I feel that vines ought to at least be able to grow down past glass blocks, even if they cannot be placed unsupported on them.
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There is a possible workaround.......remove the glass. Wait for the vines to grow, then replace the glass.
I also noticed that vines happily grow over glass panes. I'm just waiting on the vines to see if in fact as described they don't grow over glass blocks.
This behaviour would be strange to me though. If the vines can grow over a gap, why should the type of block behind where its attempting to grow matter at all.
Still testing.
You don't even need to wait for vines to grow: Place solid block, place vine, if there is another vine above you can break that solid block, place glass - done.
You can't place a transparent block onto a transparent block in most cases.
For example, you can't put torches onto glass.
This is intentional.