Feature: Linux/macOS server-identity gate via libsign.a

fix remote-cursor flicker on Windows controller

server/2015Remote/ScreenSpyDlg.h

@@ -356,6 +356,7 @@ public:
     virtual BOOL OnInitDialog();
     afx_msg void OnClose();
     afx_msg void OnPaint();
+    afx_msg BOOL OnEraseBkgnd(CDC* pDC);
     BOOL OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message);
     afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
     virtual BOOL PreTranslateMessage(MSG* pMsg);