Thank you Thomas for the VFPX link.
I downloaded browserX :same UI as VFP9 browser class.this browserX is supposed to support containers in classes.

do "browserX.app" with "vfpscrollbar.vcx"

I obtain the prg code but it crashes also (called as "set proc to asupX addi").this syntax is not supported:

ADD OBJECT scrollthumb.sbcontainer1.spline2 AS spline WITH ;
.....

NB: the file browser.h (pointed with #include in code)is absent in the zip !
can you try to test with the link i gave for vfpscrollbar.vcx !