gschem page manager forgets pages when going up

[KaiMartin]

In the current git head version of gschem the page manager sometimes drops entries when navigating a hierarchy.

This is a regression. Traditionally, the page manager used to remember all pages until they are explicitely closed. This came handy when working with a hierarchy.

To reproduce:

1) open the top page of the hierachy example in
      geda-gaf/example/gTAG
   gschem gTAG.sch

2) open page manager ([P M])

3) select sub sheet symbol "gTAG-psu"

4) go down Schematics ([shift+H S])

5) go up ([shift+H U])

6) select "gTAG-jtagio.sch"

7) go down Schematics ([shift+H S])

expected outcome:
 The page manager adds the entry "gTAG-jtagio.sch" to the tree of pages

actual outcome:
 The page manager drops the entry "gTAG-psu.sch" and replaces it with "gTAG-jtagio.sch"

There other ways to get similar misbehaviour. I found no general rule. Sometimes pages are dropped, sometimes they persist in the page manager.

---<)kaimartin(>---