That is the Offset Gable Overhang, so it doesn't stretch the roof (as defined by pivot lines) but just graphically defines the gable overhang.
It should be noted that when selecting eaves edges we get the same symbol/command as for the pivot line (offset edge). Can't really see the logic behind that and I guess that is just another effect of fragmentet armchair development.
The OPs images show the Edge Offset selected on the floor plan which defines the distance from the edge selected, in this case the gable, to the reference line. Offset Gable Overhang has the same definition, just that it is limited to gables... So, what is not stretching and just graphical?
I read the question as wanting to stretch the roof edge, since that's what can't be done from the shown pet palette. But yes, the images actually seem to show an attempt to stretch the overhang and if so then it is just a question of the OP looking for the wrong icon.
Thesleepofreason, you said the offset gable overhang button "graphically defines the gable overhang". How does that work? When I try to use it, nothing happens. What I am really after is to stretch the eave overhang/offset in 3d without changing the roof itself (not moving the blue roof reference lines). It appears impossible. For the life of me I cannot figure out what the "offset gable overhang" button in the pet pallet even does in 2d or 3d.
You have to set the Eaves Overhang setting to Offset and not Manual for the Offset Gable Overhang tool to work.
The roof tool is quite a mess. The eaves are offset with only Offset Edge tool in both 2D and 3D and gables are offset with both Offset Edge and Offset Gable Overhang in 2D but only Offset Gable Overhang in 3D. Unless you have modified the line of the gable because then you can use only Offset Edge in both 2D and 3D - which works with Eaves Overhang set to normal.
And GS don't feel a urgent need to work on every existing tools in each new version.....