[gimp] Issue #2664: add a tooltip to "better compression" checkbox.

[Jehan <jehanp src gnome org>]

commit c3ac722995667b27c2b315dd395f726e940553c7
Author: Jehan <jehan girinstud io>
Date:   Sat Dec 15 21:47:14 2018 +0100

    Issue #2664: add a tooltip to "better compression" checkbox.
    
    Zlib is a "better" compression in the meaning that it is a more advanced
    and complex algorithm than RLE. And in most cases, it should end up in
    smaller file sizes. But as any algorithm, there may be cases when the
    expectations are not met (worst cases or such). That's the nature of the
    maths. Still we should not make the checkbox text over-complicated (it
    is not the place to teach algorithmic), yet we can at least add a small
    tooltip text.

 app/widgets/gimpsavedialog.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/app/widgets/gimpsavedialog.c b/app/widgets/gimpsavedialog.c
index e215e377e1..b2eed56f9a 100644
--- a/app/widgets/gimpsavedialog.c
+++ b/app/widgets/gimpsavedialog.c
@@ -324,6 +324,9 @@ gimp_save_dialog_add_extra_widgets (GimpSaveDialog *dialog)
   /* Compression toggle. */
   compression_toggle =
     gtk_check_button_new_with_label (_("Save this XCF file with better but slower compression"));
+  gtk_widget_set_tooltip_text (compression_toggle,
+                               _("On edge cases, better compression algorithms might still "
+                                 "end up on bigger file size; manual check recommended"));
 
   dialog->compression_frame = gimp_frame_new (NULL);
   gtk_frame_set_label_widget (GTK_FRAME (dialog->compression_frame), compression_toggle);