sort signals in dbc editor by start bit

dbc/dbcmaineditor.cpp

@@ -462,7 +462,7 @@ QString DBCMainEditor::createSignalText(DBC_SIGNAL *sig)
 //Signals can have a hierarchial relationship with other signals so this function is separate and calls itself recursively to build the tree
 void DBCMainEditor::processSignalToTree(QTreeWidgetItem *parent, DBC_SIGNAL *sig)
 {
-    QTreeWidgetItem *sigItem = new QTreeWidgetItem(parent);
+    QTreeWidgetSignalItem *sigItem = new QTreeWidgetSignalItem(parent);
     QString sigInfo = createSignalText(sig);
     sigItem->setText(0, sigInfo);
     if (sig->isMultiplexor) sigItem->setIcon(0, multiplexorSignalIcon);

dbc/dbcmaineditor.h

@@ -18,6 +18,20 @@ namespace Ui {
 class DBCMainEditor;
 }
 
+class QTreeWidgetSignalItem : public QTreeWidgetItem
+{
+public:
+    using QTreeWidgetItem::QTreeWidgetItem;
+
+    // DBCSignalHandler::getSignalsAsList returns a list sorted by start bit
+    // becuase C++ uses a stable sorting algorithm (also for sorting QTreeWidgetItems) the order is not changed if the comparison function always returns false
+    bool operator<(const QTreeWidgetItem &other) const override
+    {
+        Q_UNUSED(other);
+        return false;
+    }
+};
+
 enum DBCItemTypes
 {
     NODE = 1,