save/restore collapsed state

git-svn-id: svn://db.shs.com.ru/libs@16 a8b55f48-bf90-11e4-a774-851b48703e85

kx_tools/kx_pult.cpp

@@ -665,6 +665,13 @@ bool KX_Pult::calculateExpression(int i, QVector<int> trace) {
 	trace << i;
 	QTreeWidgetItem * ti = ui->treeK->topLevelItem(i);
 	QString expr = ti->text(2);
+	if (expr.isEmpty() || expr == "0" || expr == "0,00000000" || expr == "0.00000000") {
+		markNormal(ti);
+		calculated << i;
+		K[i] = 0.;
+		ti->setText(3, "0");
+		return true;
+	}
 	//ti->setToolTip(2, QString());
 	if (!eval.check(expr)) {
 		markError(ti, eval.error());