Do not record undo in the tabularFeatures helper

Since the low-level version of tabular features is only called by the high-level one, it does not make sense to record undo there. It is much better to do it once in the high-level handler, rather than 37 times (yes!) at lower level when the tabular GUI calls tabular-feature with all the settings at once.

With large tables, this avoids to keep 37 copies of the table in Undo stack.

src/insets/InsetTabular.cpp

@@ -5348,6 +5348,8 @@ void InsetTabular::movePrevCell(Cursor & cur, EntryDirection entry_from)
 
 bool InsetTabular::tabularFeatures(Cursor & cur, string const & argument)
 {
+	cur.recordUndoInset(ATOMIC_UNDO, this);
+
 	istringstream is(argument);
 	string s;
 	is >> s;
@@ -5479,8 +5481,6 @@ void InsetTabular::tabularFeatures(Cursor & cur,
 		break;
 	}
 
-	cur.recordUndoInset(ATOMIC_UNDO, this);
-
 	getSelection(cur, sel_row_start, sel_row_end, sel_col_start, sel_col_end);
 	row_type const row = tabular.cellRow(cur.idx());
 	col_type const column = tabular.cellColumn(cur.idx());

src/insets/InsetTabular.h

@@ -882,9 +882,9 @@ public:
 	/// get offset of this cursor slice relative to our upper left corner
 	void cursorPos(BufferView const & bv, CursorSlice const & sl,
 		bool boundary, int & x, int & y) const;
-	///
+	/// Executes a space-separated sequence of tabular-features requests
 	bool tabularFeatures(Cursor & cur, std::string const & what);
-	///
+	/// Change a single tabular feature; does not handle undo.
 	void tabularFeatures(Cursor & cur, Tabular::Feature feature,
 			     std::string const & val = std::string());
 	/// number of cells

status.21x

@@ -156,6 +156,8 @@ What's new
 
 - Allow quotes in PDF text properties (bug 9830).
 
+- Avoid clogging the undo stack with useless entries when using the
+  tabular dialog (bug 9960).
 
 
 * DOCUMENTATION AND LOCALIZATION