[gtk/1371-flickering-tooltips-if-no-mouse-cursor-theme-loaded-gtk3] Tooltip: Fix the used cursor size if 0 in Settings

[Daniel Boles <dboles src gnome org>]

commit 9b7d886b723132eade2e76f3fd179cf81b7601f2
Author: Daniel Boles <dboles src gmail com>
Date:   Sun Oct 7 18:15:09 2018 +0100

    Tooltip: Fix the used cursor size if 0 in Settings
    
    Before the recent rework of positioning in GtkTooltip, the widget always
    used the cursor_size of the GdkDisplay. That work redid this to instead
    take GtkSettings::gtk-cursor-theme-size. But that property's doc says:
    
    > Size to use for cursors, or 0 to use the default size.
    
    and has 0 as its default. This is quite a likely scenario for anyone
    whose desktop or settings.ini does not explicitly provide a cursor size,
    which is the case for XFCE and win32, to name just two common platforms.
    
    Then, it seems getting a cursor_size of 0 causes GtkTooltip to freak out
    and hide/show itself at a very rapid speed, thus making it unusable.
    
    So, we should check whether the Settings return 0 and, if so, still use
    gdk_display_get_default_cursor_size (display) to ensure we get a size.
    
    https://gitlab.gnome.org/GNOME/gtk/issues/1371

 gtk/gtktooltip.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gtk/gtktooltip.c b/gtk/gtktooltip.c
index f9156624ed..e5fc5dbdaa 100644
--- a/gtk/gtktooltip.c
+++ b/gtk/gtktooltip.c
@@ -898,6 +898,9 @@ gtk_tooltip_position (GtkTooltip *tooltip,
                 "gtk-cursor-theme-size", &cursor_size,
                 NULL);
 
+  if (cursor_size == 0)
+    cursor_size = gdk_display_get_default_cursor_size (display);
+
   if (device)
     anchor_rect_padding = MAX (4, cursor_size - 32);
   else