poISelectionSet Clear

To create a selection set containing all nodes, make it visible in the graphic area, and use Clear to reset it:

hwi OpenStack
hwi GetSessionHandle session_handle
session_handle GetProjectHandle project_handle
project_handle GetPageHandle page_handle [project_handle GetActivePage]
page_handle GetWindowHandle window_handle [page_handle GetActiveWindow]
window_handle GetClientHandle client_handle
client_handle GetModelHandle model_handle [client_handle GetActiveModel]
set selection_set_id [model_handle AddSelectionSet node]

model_handle GetSelectionSetHandle selection_set_handle $selection_set_id
selection_set_handle SetLabel "OurNodeSelectionSet"
selection_set_handle SetVisibility true

puts "SelectModeList: [selection_set_handle GetSelectModeList]"
selection_set_handle SetSelectMode all
puts "Size using SelectMode all:  [selection_set_handle GetSize] [selection_set_handle GetType]s"
selection_set_handle Clear

#hide part of the model using the model browser now
selection_set_handle SetSelectMode displayed
puts "Size using SelectMode displayed:  [selection_set_handle GetSize] [selection_set_handle GetType]s"

hwi CloseStack