Fixed Issue #14: Synergy client on windows will not bring up desktop after screen powersave

lib/arch/CArchMiscWindows.cpp

@@ -414,3 +414,26 @@ CArchMiscWindows::dummySetThreadExecutionState(DWORD)
 	// do nothing
 	return 0;
 }
+
+void
+CArchMiscWindows::wakeupDisplay()
+{
+	// We can't use ::setThreadExecutionState here because it sets
+	// ES_CONTINUOUS, which we don't want.
+
+	if (s_stes == NULL) {
+		HINSTANCE kernel = LoadLibrary("kernel32.dll");
+		if (kernel != NULL) {
+			s_stes = reinterpret_cast<STES_t>(GetProcAddress(kernel,
+							"SetThreadExecutionState"));
+		}
+		if (s_stes == NULL) {
+			s_stes = &CArchMiscWindows::dummySetThreadExecutionState;
+		}
+	}
+
+	s_stes(ES_DISPLAY_REQUIRED);
+
+	// restore the original execution states
+	setThreadExecutionState(s_busyState);
+}

lib/arch/CArchMiscWindows.h

@@ -161,6 +161,9 @@ public:
 	//! Enable power saving
 	static void			removeBusyState(DWORD busyModes);
 
+	//! Briefly interrupt power saving
+	static void			wakeupDisplay();
+
 private:
 	//! Open and return a registry key, closing the parent key
 	static HKEY			openKey(HKEY parent, const TCHAR* child, bool create);

lib/platform/CMSWindowsScreen.cpp

@@ -263,6 +263,16 @@ CMSWindowsScreen::enter()
 
 		// all messages prior to now are invalid
 		nextMark();
+	} else {
+		// Entering a secondary screen. Ensure that no screensaver is active
+		// and that the screen is not in powersave mode.
+		CArchMiscWindows::wakeupDisplay();
+
+		if(m_screensaver != NULL && m_screensaverActive)
+		{
+			m_screensaver->deactivate();
+			m_screensaverActive = 0;
+		}
 	}
 
 	// now on screen