Notification_Server: Added ability to choose position of notifications

The feature gives user ability to choose the position of notifications
out of Follow Deskbar, Lower Right, Lower Left, Upper Right and Upper
Left. Fixes #9749 - Notification_Server: add the ability to choose the
position of notifications (easy).

Signed-off-by: Adrien Destugues <[email protected]>

headers/private/notification/Notifications.h

@@ -6,10 +6,13 @@
 #define _NOTIFICATIONS_H
 
 #include <Mime.h>
+#include <View.h>
 #include <String.h>
 
 #define kNotificationServerSignature "application/x-vnd.Haiku-notification_server"
 
+#define B_FOLLOW_DESKBAR B_FOLLOW_NONE
+
 // Messages
 const uint32 kNotificationMessage = 'nssm';
 
@@ -21,6 +24,7 @@ extern const char* kAutoStartName;
 extern const char* kTimeoutName;
 extern const char* kWidthName;
 extern const char* kIconSizeName;
+extern const char* kNotificationPositionName;
 
 // General default settings
 const bool kDefaultAutoStart = true;
@@ -32,5 +36,6 @@ const float kMinimumWidth = 300.0f;
 const float kMaximumWidth = 1000.0f;
 const int32 kWidthStep = 50;
 const icon_size kDefaultIconSize = B_LARGE_ICON;
+const uint32 kDefaultNotificationPosition = B_FOLLOW_DESKBAR;
 
 #endif	// _NOTIFICATIONS_H