updated for version 7.4.616
Problem:    Cannot insert a tab in front of a block.
Solution:   Correctly compute aop->start. (Christian Brabandt)
diff --git a/src/ops.c b/src/ops.c
index a4261cb..856133c 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -2544,6 +2544,7 @@
     char_u		*firstline, *ins_text;
     struct block_def	bd;
     int			i;
+    pos_T		t1;
 
     /* edit() changes this - record it for OP_APPEND */
     bd.is_MAX = (curwin->w_curswant == MAXCOL);
@@ -2617,8 +2618,16 @@
 	}
     }
 
+    t1 = oap->start;
     edit(NUL, FALSE, (linenr_T)count1);
 
+    /* When a tab was inserted, and the characters in front of the tab
+     * have been converted to a tab as well, the column of the cursor
+     * might have actually been reduced, so need to adjust here. */
+    if (t1.lnum == curbuf->b_op_start_orig.lnum
+	    && lt(curbuf->b_op_start_orig, t1))
+	oap->start = curbuf->b_op_start_orig;
+
     /* If user has moved off this line, we don't know what to do, so do
      * nothing.
      * Also don't repeat the insert when Insert mode ended with CTRL-C. */
@@ -2644,10 +2653,11 @@
 #endif
 			)
 	    {
+		int t = getviscol2(curbuf->b_op_start_orig.col,
+					      curbuf->b_op_start_orig.coladd);
 		oap->start.col = curbuf->b_op_start_orig.col;
-		pre_textlen -= getviscol2(oap->start.col, oap->start.coladd)
-							    - oap->start_vcol;
-		oap->start_vcol = getviscol2(oap->start.col, oap->start.coladd);
+		pre_textlen -= t - oap->start_vcol;
+		oap->start_vcol = t;
 	    }
 	    else if (oap->op_type == OP_APPEND
 		      && oap->end.col
@@ -2660,12 +2670,13 @@
 #endif
 			)
 	    {
+		int t = getviscol2(curbuf->b_op_start_orig.col,
+					      curbuf->b_op_start_orig.coladd);
 		oap->start.col = curbuf->b_op_start_orig.col;
 		/* reset pre_textlen to the value of OP_INSERT */
 		pre_textlen += bd.textlen;
-		pre_textlen -= getviscol2(oap->start.col, oap->start.coladd)
-							    - oap->start_vcol;
-		oap->start_vcol = getviscol2(oap->start.col, oap->start.coladd);
+		pre_textlen -= t - oap->start_vcol;
+		oap->start_vcol = t;
 		oap->op_type = OP_INSERT;
 	    }
 	}
diff --git a/src/testdir/test39.in b/src/testdir/test39.in
index c4e46ff..fcb935d 100644
--- a/src/testdir/test39.in
+++ b/src/testdir/test39.in
Binary files differ
diff --git a/src/testdir/test39.ok b/src/testdir/test39.ok
index 5c517e2..349d67f 100644
--- a/src/testdir/test39.ok
+++ b/src/testdir/test39.ok
Binary files differ
diff --git a/src/version.c b/src/version.c
index f278cda..2c21e4a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    616,
+/**/
     615,
 /**/
     614,