[gimp] Bug 750954 - Make tips of the "Black point" and "White point" buttons...

[Michael Natterer <mitch src gnome org>]

commit e2bdfd41e2ff5829ef4ece766195f071e3428bf5
Author: Michael Natterer <mitch gimp org>
Date:   Mon Aug 31 00:07:59 2015 +0200

    Bug 750954 - Make tips of the "Black point" and "White point" buttons...
    
    ...in the Levels dialog explain the difference between them
    
    Improve the tooltips of the pick buttons to say
    
    "Pick FOO point for {all channels|the selected channel}"

 app/tools/gimplevelstool.c |   26 ++++++++++++++++++++++----
 1 files changed, 22 insertions(+), 4 deletions(-)
---
diff --git a/app/tools/gimplevelstool.c b/app/tools/gimplevelstool.c
index 5c22ad1..3300bfb 100644
--- a/app/tools/gimplevelstool.c
+++ b/app/tools/gimplevelstool.c
@@ -274,21 +274,37 @@ gimp_levels_tool_color_picker_new (GimpLevelsTool *tool,
 {
   const gchar *icon_name;
   const gchar *help;
+  gboolean     all_channels = (value & PICK_ALL_CHANNELS) != 0;
 
   switch (value & 0xF)
     {
     case PICK_LOW_INPUT:
       icon_name = GIMP_STOCK_COLOR_PICKER_BLACK;
-      help      = _("Pick black point");
+
+      if (all_channels)
+        help = _("Pick black point for all channels");
+      else
+        help = _("Pick black point for the selected channel");
       break;
+
     case PICK_GAMMA:
       icon_name = GIMP_STOCK_COLOR_PICKER_GRAY;
-      help      = _("Pick gray point");
+
+      if (all_channels)
+        help = _("Pick gray point for all channels");
+      else
+        help = _("Pick gray point for the selected channel");
       break;
+
     case PICK_HIGH_INPUT:
       icon_name = GIMP_STOCK_COLOR_PICKER_WHITE;
-      help      = _("Pick white point");
+
+      if (all_channels)
+        help = _("Pick white point for all channels");
+      else
+        help = _("Pick whitw point for the selected channel");
       break;
+
     default:
       return NULL;
     }
@@ -561,7 +577,9 @@ gimp_levels_tool_dialog (GimpImageMapTool *image_map_tool)
 
   button = gtk_button_new_with_mnemonic (_("_Auto"));
   gtk_box_pack_start (GTK_BOX (hbbox), button, FALSE, FALSE, 0);
-  gimp_help_set_help_data (button, _("Adjust levels automatically"), NULL);
+  gimp_help_set_help_data (button,
+                           _("Adjust levels for all channels automatically"),
+                           NULL);
   gtk_widget_show (button);
 
   g_signal_connect (button, "clicked",