Fix exported tile sets file extension

src/QtLocationPlugin/QMLControl/OfflineMap.qml

@@ -35,6 +35,7 @@ Item {
     property var    _settingsManager:   QGroundControl.settingsManager
     property var    _settings:          _settingsManager ? _settingsManager.offlineMapsSettings : null
     property var    _fmSettings:        _settingsManager ? _settingsManager.flightMapSettings : null
+    property var    _appSettings:       _settingsManager.appSettings
     property Fact   _mapboxFact:        _settingsManager ? _settingsManager.appSettings.mapboxToken : null
     property Fact   _mapboxAccountFact: _settingsManager ? _settingsManager.appSettings.mapboxAccount : null
     property Fact   _mapboxStyleFact:   _settingsManager ? _settingsManager.appSettings.mapboxStyle : null
@@ -213,7 +214,8 @@ Item {
     QGCFileDialog {
         id:             fileDialog
         folder:         QGroundControl.settingsManager.appSettings.missionSavePath
-        nameFilters:    ["Tile Sets (*.qgctiledb)"]
+        nameFilters:    [ qsTr("Tile Sets (*.%1)").arg(defaultSuffix) ]
+        defaultSuffix:  _appSettings.tilesetFileExtension
 
         onAcceptedForSave: {
             if (QGroundControl.mapEngineManager.exportSets(file)) {

src/Settings/AppSettings.cc

@@ -30,6 +30,7 @@ const char* AppSettings::telemetryFileExtension =   "tlog";
 const char* AppSettings::kmlFileExtension =         "kml";
 const char* AppSettings::shpFileExtension =         "shp";
 const char* AppSettings::logFileExtension =         "ulg";
+const char* AppSettings::tilesetFileExtension =     "qgctiledb";
 
 const char* AppSettings::parameterDirectory =       QT_TRANSLATE_NOOP("AppSettings", "Parameters");
 const char* AppSettings::telemetryDirectory =       QT_TRANSLATE_NOOP("AppSettings", "Telemetry");

src/Settings/AppSettings.h

@@ -89,6 +89,7 @@ public:
     Q_PROPERTY(QString kmlFileExtension         MEMBER kmlFileExtension         CONSTANT)
     Q_PROPERTY(QString shpFileExtension         MEMBER shpFileExtension         CONSTANT)
     Q_PROPERTY(QString logFileExtension         MEMBER logFileExtension         CONSTANT)
+    Q_PROPERTY(QString tilesetFileExtension     MEMBER tilesetFileExtension     CONSTANT)
 
     QString missionSavePath       ();
     QString parameterSavePath     ();
@@ -115,7 +116,8 @@ public:
     static const char* kmlFileExtension;
     static const char* shpFileExtension;
     static const char* logFileExtension;
-
+    static const char* tilesetFileExtension;
+    
     // Child directories of savePath for specific file types
     static const char* parameterDirectory;
     static const char* telemetryDirectory;