[gtk/cherry-pick-4ba89f25] cellarea: Don't shrink area too much

[Benjamin Otte <otte src gnome org>]

commit 16ff055b42b71dc01aa48e45c551cd207f6f992b
Author: Benjamin Otte <otte redhat com>
Date:   Tue Jun 15 19:34:37 2021 +0200

    cellarea: Don't shrink area too much
    
    Do not compute rectangles with negative width/height. This avoids
    assertion failures further down when those rectangles were actually
    checked.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1962215
    
    
    (cherry picked from commit 4ba89f25b8a88616afc1915bdb4fb87d13efae6f)

 gtk/gtkcellarea.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/gtk/gtkcellarea.c b/gtk/gtkcellarea.c
index a46d50900b..7541e60ef8 100644
--- a/gtk/gtkcellarea.c
+++ b/gtk/gtkcellarea.c
@@ -3423,8 +3423,18 @@ gtk_cell_area_inner_cell_area (GtkCellArea        *area,
 
   *inner_area = *cell_area;
 
+  if (border.left + border.right > cell_area->width)
+    {
+      border.left = cell_area->width / 2;
+      border.right = (cell_area->width + 1) / 2;
+    }
   inner_area->x += border.left;
   inner_area->width -= border.left + border.right;
+  if (border.top + border.bottom > cell_area->height)
+    {
+      border.top = cell_area->height / 2;
+      border.bottom = (cell_area->height + 1) / 2;
+    }
   inner_area->y += border.top;
   inner_area->height -= border.top + border.bottom;
 }