Don't signal that tags changed everytime you use the configure dialog.

Check if the user modified them first.

Saves some MessageList::Core::Model::setFilter() calls, and makes
bug 261645 reproducible in less use cases.

CCBUG:261645

configuredialog.cpp

@@ -1976,12 +1976,31 @@ void AppearancePage::MessageTagTab::doLoadFromGlobalSettings()
   slotUpdateTagSettingWidgets( -1 );
   //Needed since the previous function doesn't affect add button
   mTagAddButton->setEnabled( false );
+
+  // Save the original list
+  mOriginalMsgTagList.clear();
+  foreach( const KMail::TagPtr &tag, mMsgTagList ) {
+    mOriginalMsgTagList.append( KMail::TagPtr( new KMail::Tag( *tag ) ) );
+  }
 }
 
 void AppearancePage::MessageTagTab::save()
 {
   slotRecordTagSettings( mTagListBox->currentRow() );
 
+  if ( mOriginalMsgTagList.count() == mMsgTagList.count() ) {
+    bool nothingChanged = true;
+    for ( int i=0; i<mMsgTagList.count(); ++i ) {
+      if ( *(mMsgTagList[i]) != *(mOriginalMsgTagList[i]) ) {
+        nothingChanged = false;
+        break;
+      }
+    }
+    if ( nothingChanged ) {
+      return;
+    }
+  }
+
   foreach( const KMail::Tag::Ptr &tag, mMsgTagList ) {
 
     tag->priority = mMsgTagList.indexOf( tag );

configuredialog_p.h

@@ -484,6 +484,9 @@ private: // data
   // List of all Tags currently in the list
   QList<KMail::TagPtr> mMsgTagList;
 
+  // So we can compare to mMsgTagList and see if the user changed tags
+  QList<KMail::TagPtr> mOriginalMsgTagList;
+
   /*Used to safely call slotRecordTagSettings when the selection in
     list box changes*/
   int mPreviousTag;