Do not unnecessarily reset state of spectrum demo

This patch ensures that the state of the application is not reset when:
	- Any of the 'Play generated tone', 'Play file' or settings
	dialogs are opened
	- Any of the 'Play generated tone', 'Play file' or settings
	dialogs are dismissed by pressing the Cancel button
	- A new input or output device is selected via the settings
	dialog, and that new device supports the data format which
	is currently being used within the application
	- The window function is changed via the settings dialog

Note that the application is still reset if a new input or output
device is selected via the settings dialog, and this device does not
support the current data format.

Task-number: QTBUG-12935
Task-number: QTBUG-14810

1 files changed, 1 insertions, 0 deletions

diff --git a/demos/spectrum/app/mainwidget.h b/demos/spectrum/app/mainwidget.h
index ddab8b7..cc1f9ed 100644
--- a/demos/spectrum/app/mainwidget.h
+++ b/demos/spectrum/app/mainwidget.h
@@ -89,6 +89,7 @@ private slots:
     void showToneGeneratorDialog();
     void initializeRecord();
     void dataDurationChanged(qint64 duration);
+    void updateModeMenu();
 
 private:
     void createUi();