tdehwlib: Add regular monitoring of power supply device status,

to be able to generate a signal when the power state changes,
if the signal is not generated from udev.

This resolves issue TDE/tde#30.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit fb1316c785)

tdecore/tdehw/tdehardwaredevices.cpp

@@ -212,7 +212,7 @@ TDEHardwareDevices::TDEHardwareDevices() {
 		m_deviceWatchTimer = new TQTimer(this);
 		connect( m_deviceWatchTimer, SIGNAL(timeout()), this, SLOT(processStatelessDevices()) );
 
-		// Special case for battery polling (longer delay, 5 seconds)
+		// Special case for battery and power supply polling (longer delay, 5 seconds)
 		m_batteryWatchTimer = new TQTimer(this);
 		connect( m_batteryWatchTimer, SIGNAL(timeout()), this, SLOT(processBatteryDevices()) );
 
@@ -919,6 +919,15 @@ void TDEHardwareDevices::processBatteryDevices() {
 			emit hardwareUpdated(hwdevice);
 			emit hardwareEvent(TDEHardwareEvent::HardwareUpdated, hwdevice->uniqueID());
 		}
+		else if (hwdevice->type() == TDEGenericDeviceType::PowerSupply) {
+			TDEMainsPowerDevice *pdevice = dynamic_cast<TDEMainsPowerDevice*>(hwdevice);
+			int previousOnlineState = pdevice->online();
+			rescanDeviceInformation(hwdevice, false);
+			if (pdevice->online() != previousOnlineState) {
+				emit hardwareUpdated(hwdevice);
+				emit hardwareEvent(TDEHardwareEvent::HardwareUpdated, hwdevice->uniqueID());
+			}
+		}
 	}
 }