Fix error redoing shrink fatten

Use a property to store even-offset option.

source/blender/editors/transform/transform.c

@@ -2024,6 +2024,18 @@ void saveTransform(bContext *C, TransInfo *t, wmOperator *op)
 
 		RNA_property_boolean_set_array(op->ptr, prop, constraint_axis);
 	}
+
+	{
+		const char *prop_id = NULL;
+		if (t->mode == TFM_SHRINKFATTEN) {
+			prop_id = "use_even_offset";
+		}
+
+		if (prop_id && (prop = RNA_struct_find_property(op->ptr, prop_id))) {
+
+			RNA_property_boolean_set(op->ptr, prop, (t->flag & T_ALT_TRANSFORM) != 0);
+		}
+	}
 }
 
 /* note: caller needs to free 't' on a 0 return */

source/blender/editors/transform/transform_generics.c

@@ -80,6 +80,7 @@
 #include "BKE_editmesh.h"
 #include "BKE_tracking.h"
 #include "BKE_mask.h"
+#include "BKE_utildefines.h"
 
 #include "ED_anim_api.h"
 #include "ED_armature.h"
@@ -1069,6 +1070,8 @@ static int initTransInfo_edit_pet_to_flag(const int proportional)
  * Setup internal data, mouse, vectors
  *
  * \note \a op and \a event can be NULL
+ *
+ * \see #saveTransform does the reverse.
  */
 void initTransInfo(bContext *C, TransInfo *t, wmOperator *op, const wmEvent *event)
 {
@@ -1160,6 +1163,19 @@ void initTransInfo(bContext *C, TransInfo *t, wmOperator *op, const wmEvent *eve
 		t->spacetype = sa->spacetype;
 	}
 
+	/* handle T_ALT_TRANSFORM initialization, we may use for different operators */
+	if (op) {
+		const char *prop_id = NULL;
+		if (t->mode == TFM_SHRINKFATTEN) {
+			prop_id = "use_even_offset";
+		}
+
+		if (prop_id && (prop = RNA_struct_find_property(op->ptr, prop_id)) &&
+		    RNA_property_is_set(op->ptr, prop))
+		{
+			BKE_BIT_TEST_SET(t->flag, RNA_property_boolean_get(op->ptr, prop), T_ALT_TRANSFORM);
+		}
+	}
 
 	if (t->spacetype == SPACE_VIEW3D) {
 		View3D *v3d = sa->spacedata.first;

source/blender/editors/transform/transform_ops.c

@@ -791,6 +791,8 @@ static void TRANSFORM_OT_shrink_fatten(struct wmOperatorType *ot)
 
 	RNA_def_float(ot->srna, "value", 0, -FLT_MAX, FLT_MAX, "Offset", "", -FLT_MAX, FLT_MAX);
 
+	RNA_def_boolean(ot->srna, "use_even_offset", true, "Offset Even", "Scale the offset to give more even thickness");
+
 	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR | P_SNAP);
 }