0028333: Draw Harness - whatis command hangs when selection is activated with no...

0028333: Draw Harness - whatis command hangs when selection is activated with no opened view

Added new method Draw_Window::IsMapped() for checked window state.
Draw_Window using XLib now does not exit application on closing window.
The method Draw_Viewer::Select() (called by whatis command)
has been corrected so as not to enter the loop if no views are initialized.