RNA/UI: Allow displaying in tooltip why RNA property isn't editable

This commit allows RNA properties to return additional info on their editable state which may then be displayed in tooltips. To show how it works, it also adds some info for the editable check of proxies. For generally un-editable properties or properties of a linked data-block, RNA returns default strings.

| {F362785} | {F362786} | {F362787} |

Reviewed by brecht, thanks!

Differential Revision: https://developer.blender.org/D2243

1 files changed, 7 insertions, 2 deletions

diff --git a/source/blender/makesrna/intern/rna_pose.c b/source/blender/makesrna/intern/rna_pose.c
index 1f34d8f23d4..0591e877634 100644
--- a/source/blender/makesrna/intern/rna_pose.c
+++ b/source/blender/makesrna/intern/rna_pose.c
@@ -556,13 +556,18 @@ static void rna_PoseChannel_constraints_remove(ID *id, bPoseChannel *pchan, Repo
 	}
 }
 
-static int rna_PoseChannel_proxy_editable(PointerRNA *ptr)
+static int rna_PoseChannel_proxy_editable(PointerRNA *ptr, const char **r_info)
 {
 	Object *ob = (Object *)ptr->id.data;
 	bArmature *arm = ob->data;
 	bPoseChannel *pchan = (bPoseChannel *)ptr->data;
 	
-	return (ob->proxy && pchan->bone && (pchan->bone->layer & arm->layer_protected)) ? 0 : PROP_EDITABLE;
+	if (ob->proxy && pchan->bone && (pchan->bone->layer & arm->layer_protected)) {
+		*r_info = "Can't edit property of a proxy on a protected layer";
+		return 0;
+	}
+	
+	return PROP_EDITABLE;
 }
 
 static int rna_PoseChannel_location_editable(PointerRNA *ptr, int index)