[gnome-builder] sourceview: ensure space for overlay scrollbars

[Christian Hergert <chergert src gnome org>]

commit 43436ce16857333a3f6823ebf3867d7ea3b7ece2
Author: Christian Hergert <chergert redhat com>
Date:   Fri Oct 4 17:52:49 2019 -0700

    sourceview: ensure space for overlay scrollbars

 src/libide/sourceview/ide-source-view.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/src/libide/sourceview/ide-source-view.c b/src/libide/sourceview/ide-source-view.c
index ce10cd4b7..508ccc463 100644
--- a/src/libide/sourceview/ide-source-view.c
+++ b/src/libide/sourceview/ide-source-view.c
@@ -3868,6 +3868,12 @@ ide_source_view_set_overscroll_num_lines (IdeSourceView *self,
 
   new_margin = CLAMP (new_margin, 0, MAX (height - priv->cached_char_height, 0));
 
+  /* ensure enough space for the overlay scrollbars and their interactive
+   * trough when scrolled to the end.
+   */
+  if (new_margin < 16)
+    new_margin = 16;
+
   g_object_set (self,
                 "bottom-margin", new_margin,
                 NULL);