fix pcbnew file save as problem, if previous file by same basename did not...

fix pcbnew file save as problem, if previous file by same basename did not exist.  Show default file ext.

pcbnew/files.cpp

@@ -415,7 +415,14 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
         wildcard << wxGetTranslation( PcbFileWildcard ) << wxChar( '|' ) <<
                     wxGetTranslation( LegacyPcbFileWildcard );
 
-        wxFileDialog dlg( this, _( "Save Board File As" ), wxEmptyString, GetBoard()->GetFileName(),
+        pcbFileName = GetBoard()->GetFileName();
+
+        // Match the default wildcard filter choice, with the inital file extension shown.
+        // That'll be the extension unless user changes filter dropdown listbox.
+        pcbFileName.SetExt( KiCadPcbFileExtension );
+
+        wxFileDialog dlg(   this, _( "Save Board File As" ), wxEmptyString,
+                            pcbFileName.GetFullPath(),
                             wildcard, wxFD_SAVE
                             /* wxFileDialog is not equipped to handle multiple wildcards and
                                 wxFD_OVERWRITE_PROMPT both together.
@@ -431,6 +438,7 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
         pluginType = ( filterNdx == 1 ) ? IO_MGR::LEGACY : IO_MGR::KICAD;
 
         // Note: on Linux wxFileDialog is not reliable for noticing a changed filename.
+        // We probably need to file a bug report or implement our own derivation.
 
         pcbFileName = dlg.GetPath();
 
@@ -487,7 +495,6 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
         else
         {
             backupFileName.Clear();
-            saveok = false;
         }
     }