WowAce

The border of TreeGroup is anchored to both "treeframe" and "frame" which hinders the dragger to work:

	local border = CreateFrame("Frame", nil, frame, "BackdropTemplate")
	border:SetPoint("TOPLEFT", treeframe, "TOPRIGHT")
	border:SetPoint("BOTTOMRIGHT")

This is related to this UI issue, so that no error is raised, even though it should: https://github.com/Stanzilla/WoWUIBugs/issues/136 (this issue is only about the missing error, the Blizzard UI works "as expected")

When anchoring "border" to only "frame" OR "freeframe" resizing works right away (even though the border is not positioned correctly):

	local border = CreateFrame("Frame", nil, frame, "BackdropTemplate")
	border:SetPoint("TOPLEFT", frame, "TOPRIGHT")
	border:SetPoint("BOTTOMRIGHT")

The double anchoring is most likely to make sure it resizes correctly when the dragger is moved, so not sure what's the best way to fix this.