Tab key corrected in Save dialog (surge-synthesizer#641)

With the restoration of key bindings, the Tab toggled
modulation. That interfered with the save dialog.
So have the GUI editor not bind and eat the tab key
if the saveDialog is visible.

Closes surge-synthesizer#633 - tab key interfering with store

Former-commit-id: 02df69b2597c900065a0415d3d1684a58d4b6133 [formerly b888368]
Former-commit-id: a43c751db59f03f47e9d22c1cbbf03ef71ac5297
Former-commit-id: 964191f9ed5d89c09f08c76042a51487956b8350

src/common/gui/SurgeGUIEditor.cpp

@@ -506,6 +506,13 @@ int32_t SurgeGUIEditor::onKeyDown(const VstKeyCode& code, CFrame* frame)
         switch (code.virt)
         {
         case VKEY_TAB:
+            if (saveDialog && saveDialog->isVisible())
+            {
+               /* 
+               ** SaveDialog gets access to the tab key to switch between fields if it is open
+               */
+               return -1;
+            }
             toggle_mod_editing();
             return 1;
 #if !LINUX