[gnumeric] SheetControlGUI: Fix potential crasher.

[Morten Welinder <mortenw src gnome org>]

commit 476f2c14ec52092c37db7f53cdfde386de6bdb3f
Author: Morten Welinder <terra gnome org>
Date:   Sat Dec 26 20:38:47 2015 -0500

    SheetControlGUI: Fix potential crasher.
    
    We're not derived from GtkWidget, so casting the class to that and
    setting vtable entries will not end well.

 ChangeLog               |    4 ++++
 NEWS                    |    3 +++
 src/sheet-control-gui.c |   32 +++++++++++++++++---------------
 3 files changed, 24 insertions(+), 15 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index b34ddc0..eda8ff5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2015-12-26  Morten Welinder  <terra gnome org>
 
+       * src/sheet-control-gui.c (sheet_control_gui_new): Hook up screen
+       change here (on the grid).
+       (scg_class_init): Not here.  We're not derived from GtkWidget.
+
        * src/sheet-style.c (foreach_tile_r): Rename from foreach_tile.
        (foreach_tile): New top-level function taking few parameters.  All
        callers changed.
diff --git a/NEWS b/NEWS
index 56218d1..fdb2c2c 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,8 @@
 Gnumeric 1.12.26
 
+Morten:
+       * Fix potential crasher on showing initial window.
+
 --------------------------------------------------------------------------
 Gnumeric 1.12.25
 
diff --git a/src/sheet-control-gui.c b/src/sheet-control-gui.c
index 276bc32..fff1753 100644
--- a/src/sheet-control-gui.c
+++ b/src/sheet-control-gui.c
@@ -1565,6 +1565,18 @@ sheet_object_key_pressed (G_GNUC_UNUSED GtkWidget *w, GdkEventKey *event, SheetC
        return TRUE;
 }
 
+static void
+cb_screen_changed (GtkWidget *widget, G_GNUC_UNUSED GdkScreen *prev,
+                  SheetControlGUI *scg)
+{
+       GdkScreen *screen = gtk_widget_get_screen (widget);
+
+       if (screen) {
+               scg->screen_width = gdk_screen_get_width (screen);
+               scg->screen_height = gdk_screen_get_height (screen);
+       }
+}
+
 SheetControlGUI *
 sheet_control_gui_new (SheetView *sv, WBCGtk *wbcg)
 {
@@ -1765,6 +1777,11 @@ sheet_control_gui_new (SheetView *sv, WBCGtk *wbcg)
                 NULL);
        g_object_ref (scg->label);
 
+       g_signal_connect (G_OBJECT (scg->grid),
+                         "screen-changed",
+                         G_CALLBACK (cb_screen_changed),
+                         scg);
+
        return scg;
 }
 
@@ -3886,22 +3903,9 @@ scg_show_im_tooltip (SheetControl *sc, GnmInputMsg *im, GnmCellPos *pos)
 
 
 static void
-scg_screen_changed (GtkWidget *widget, G_GNUC_UNUSED GdkScreen *prev)
-{
-       SheetControlGUI *scg = (SheetControlGUI *)widget;
-       GdkScreen *screen = gtk_widget_get_screen (widget);
-
-       if (screen) {
-               scg->screen_width = gdk_screen_get_width (screen);
-               scg->screen_height = gdk_screen_get_height (screen);
-       }
-}
-
-static void
 scg_class_init (GObjectClass *object_class)
 {
        SheetControlClass *sc_class = SHEET_CONTROL_CLASS (object_class);
-       GtkWidgetClass *wclass = (GtkWidgetClass *)object_class;
 
        g_return_if_fail (sc_class != NULL);
 
@@ -3909,8 +3913,6 @@ scg_class_init (GObjectClass *object_class)
 
        object_class->finalize = scg_finalize;
 
-       wclass->screen_changed = scg_screen_changed;
-
        sc_class->resize                   = scg_resize_virt;
        sc_class->redraw_all               = scg_redraw_all;
        sc_class->redraw_range             = scg_redraw_range;