Make FilePropertyWidget use default extension.

Before these changes it was using default extension for save dialogs only.
The point here is that code for save and load dialogs is doing almost the
same thing and should probably be moved to a single method. Additionally,
for some reason load dialogs are using ".ext (*.ext)" approach, while
save dialogs are displaying "*.ext" straight away. Somebody should probably
take a look at that as a maintenance.

Refs #7772

Code/Mantid/MantidQt/API/src/FilePropertyWidget.cpp

@@ -94,20 +94,29 @@ namespace API
   /** For file dialogs
    *
    * @param exts :: vector of extensions
+   * @param defaultExt :: default extension to use
    * @return a string that filters files by extenstions
    */
-  QString getFileDialogFilter(const std::set<std::string> & exts)
+  QString getFileDialogFilter(const std::set<std::string>& exts, const std::string& defaultExt)
   {
-    QString filter;
+    QString filter("");
+
+    if( !defaultExt.empty() )
+    {
+      filter.append(QString::fromStdString(defaultExt) + " (*" + QString::fromStdString(defaultExt) + ");;");
+    }
+
     if( !exts.empty() )
     {
       // --------- Load a File -------------
-      filter = "";
       std::set<std::string>::const_iterator iend = exts.end();
       // Push a wild-card onto the front of each file suffix
       for( std::set<std::string>::const_iterator itr = exts.begin(); itr != iend; ++itr)
       {
-        filter.append(QString::fromStdString(*itr) + " (*" + QString::fromStdString(*itr) + ");;");
+        if( (*itr) != defaultExt )
+        {
+          filter.append(QString::fromStdString(*itr) + " (*" + QString::fromStdString(*itr) + ");;");
+        }
       }
       filter.trimmed();
     }
@@ -129,6 +138,7 @@ namespace API
 
     //The allowed values in this context are file extensions
     std::set<std::string> exts = prop->allowedValues();
+    std::string defaultExt = prop->getDefaultExt();
 
     /* MG 20/07/09: Static functions such as these that use native Windows and MAC dialogs
        in those environments are alot faster. This is unforunately at the expense of
@@ -137,14 +147,13 @@ namespace API
     QString filename;
     if( prop->isLoadProperty() )
     {
-      QString filter = getFileDialogFilter(exts);
+      QString filter = getFileDialogFilter(exts, defaultExt);
       filename = QFileDialog::getOpenFileName(NULL, "Open file", AlgorithmInputHistory::Instance().getPreviousDirectory(), filter);
     }
     else if ( prop->isSaveProperty() )
     {
       // --------- Save a File -------------
       //Have each filter on a separate line with the default as the first
-      std::string defaultExt = prop->getDefaultExt();
       QString filter;
       if( !defaultExt.empty() )
       {
@@ -220,7 +229,7 @@ namespace API
       dynamic_cast< Mantid::API::MultipleFileProperty* >( baseProp );
     if( !prop ) return QStringList();
 
-    QString filter = getFileDialogFilter(prop->getExts());
+    QString filter = getFileDialogFilter(prop->getExts(), prop->getDefaultExt());
     QStringList files = QFileDialog::getOpenFileNames(NULL, "Open Multiple Files", AlgorithmInputHistory::Instance().getPreviousDirectory(), filter);
 
     return files;