Handle correctly zero table special arguments.

Fixes: #10247

src/frontends/qt4/GuiTabular.cpp

@@ -33,6 +33,7 @@
 
 #include "support/convert.h"
 #include "support/debug.h"
+#include "support/lstrings.h"
 
 #include <QCheckBox>
 #include <QPushButton>
@@ -560,7 +561,7 @@ docstring GuiTabular::dialogToParams() const
 
 	// apply the special alignment
 	string special = fromqstr(specialAlignmentED->text());
-	if (special.empty())
+	if (support::trim(special).empty())
 		special = "none";
 	if (multicolumnCB->isChecked())
 		setParam(param_str, Tabular::SET_SPECIAL_MULTICOLUMN, special);

status.23x

@@ -258,6 +258,9 @@ What's new
 - Honor the syntax highlighting package choice when adding listing params
   without actually inserting a listing (bug 11151).
 
+- Handle correctly zero table special arguments (bug 10247).
+
+
 * INTERNALS
 
 - Fix bug that TeX files were not detected when reconfiguring LyX