gschem crashes on symbol-translate if there are objects in the negative

[KaiMartin]

Current git head of gschem crashes on symbol-translate if there are objects with negative coordinates.
To reproduce:

1) open gschem on a symbol

3) select an attribute

4) let the mouse hover somewhere above the attribute

5) type [m] and move the attribute below the bottom of the canvas

6) type [et] to bring up the translate symbol dialog

7) click ok
gschem crashes with a backtrace:

/---------------------------
Backtrace:
In unknown file:
   ?: 0* [#<procedure #f (arg)> (# # # # ...)]
In /usr/local/share/gEDA/scheme/gschem/deprecated.scm:
 394: 1* (if (and (not #) (null? #)) (run-hook deselect-all-hook (quote ())))
 394: 2* (and (not (null? deselect-all-hook)) (null? (page-selection (active-page))))
 395: 3 [null? ...
 395: 4* [%page-selection ...
 395: 5* [%active-page]

/usr/local/share/gEDA/scheme/gschem/deprecated.scm:395:37: In procedure %active-page in expression (active-page):
/usr/local/share/gEDA/scheme/gschem/deprecated.scm:395:37: Found invalid gEDA smob #f
\-------------------------------------------

---<)kaimartin(>---

[Gareth Edwards (gareth-uk)]

Confirmed in latest git HEAD. Doesn't need a testcase, any symbol file will do it following kmk's instructions.