thank you Walter.
A form is a big scrollable container (Vertical & horizontal with scrollbars property (0,1,2).I use often it to scroll
easily and directly without implementing a new class for scrollable container.
even a form inside a parent form can do that (showWindow=1).

i tried the flatscrollbar by personal curiosity.
what i dont understand is your sentence (my english is not great):
"The problem is that controls (like the listbox) bleed through outside of the contrainer if you click into it."
even translating it does not understanded by me ! can you be more explicit please.

without a traditional scrollbar can build a simple container with a (spinner+textbox) to scroll any vfp container with this snippet in
event "upclick" and "downclick" of the spinner;the textbox can contain a variable increment for the spinner (small or big values).

*for the spinner...scrollV
this.increment=this.parent.text1.value
With  Thisform.container1
   For Each obj In .Controls
try  &&if obj dont have top property (a timer...)
	obj.Top=obj.Top+This.Increment  && + for downlick and - for upclick
catch
endtry
  Next
Endwith

*for the spinner...scrollH
this.increment=this.parent.text1.value
With  Thisform.container1
   For Each obj In .Controls
try   &&if obj dont have left property (a timer...)
	obj.left=obj.left+This.Increment  && + for downlick and - for upclick
catch
endtry
  Next
Endwith

can make one small container class for scrollV and another for scrollH.
it can be very small class comparatively to the flatscrollbar or another vfp scroll class (as SPS or Kirov ones...can see them
in my blog)
Infortunatly vfp controls have not handles to use APIs as sendmessage to scroll...