[vte] emulation: Don't use smart tabs if the cells are already in use

[Egmont Koblinger <egmontkob src gnome org>]

commit 30a7c0b7f75fc72703e700838db1d831e90430c4
Author: Egmont Koblinger <egmont gmail com>
Date:   Wed Apr 6 10:55:57 2016 +0200

    emulation: Don't use smart tabs if the cells are already in use
    
    https://bugzilla.gnome.org/show_bug.cgi?id=764330#c3

 src/vteseq.cc |   44 ++++++++++++++++----------------------------
 1 files changed, 16 insertions(+), 28 deletions(-)
---
diff --git a/src/vteseq.cc b/src/vteseq.cc
index 5c22b29..6223ddc 100644
--- a/src/vteseq.cc
+++ b/src/vteseq.cc
@@ -1928,36 +1928,24 @@ VteTerminalPrivate::seq_tab()
                 _vte_row_data_fill (rowdata, &basic_cell.cell, newcol);
 
                /* Insert smart tab if there's nothing in the line after
-                * us.  Though, there may be empty cells (with non-default
-                * background color for example.
+                * us, not even empty cells (with non-default background
+                * color for example).
                 *
-                * Notable bugs here: 545924 and 597242 */
-               {
+                * Notable bugs here: 545924, 597242, 764330 */
+               if (col >= old_len && newcol - col <= VTE_TAB_WIDTH_MAX) {
                        glong i;
-                       gboolean found = FALSE;
-                       for (i = old_len; i > col; i--) {
-                               const VteCell *cell = _vte_row_data_get (rowdata, i - 1);
-                               if (cell->attr.fragment || cell->c != 0) {
-                                       found = TRUE;
-                                       break;
-                               }
-                       }
-                       /* Nothing found on the line after us, turn this into
-                        * a smart tab */
-                       if (!found && newcol - col <= VTE_TAB_WIDTH_MAX) {
-                               VteCell *cell = _vte_row_data_get_writable (rowdata, col);
-                               VteCell tab = *cell;
-                               tab.attr.columns = newcol - col;
-                               tab.c = '\t';
-                               /* Save tab char */
-                               *cell = tab;
-                               /* And adjust the fragments */
-                               for (i = col + 1; i < newcol; i++) {
-                                       cell = _vte_row_data_get_writable (rowdata, i);
-                                       cell->c = '\t';
-                                       cell->attr.columns = 1;
-                                       cell->attr.fragment = 1;
-                               }
+                       VteCell *cell = _vte_row_data_get_writable (rowdata, col);
+                       VteCell tab = *cell;
+                       tab.attr.columns = newcol - col;
+                       tab.c = '\t';
+                       /* Save tab char */
+                       *cell = tab;
+                       /* And adjust the fragments */
+                       for (i = col + 1; i < newcol; i++) {
+                               cell = _vte_row_data_get_writable (rowdata, i);
+                               cell->c = '\t';
+                               cell->attr.columns = 1;
+                               cell->attr.fragment = 1;
                        }
                }