class_docstr: A dialog for "selecting" items on a tree by checking them
class_docstr_tok: ["A","dialog","for","``","selecting","''","items","on","a","tree","by","checking","them"]
code: def on_left_down(self, event):
      item_id, where = self.tree_ctrl.HitTest(event.Position)
      if where & wx.TREE_HITTEST_ONITEMICON == 0:
          event.Skip()
          return
  
      d = self.get_item_data(item_id)
      if d[None] is None or d[None] is False:
          state = True
      else:
          state = False
      self.set_item_state(item_id, state)
      self.set_parent_state(item_id)
  
file_path: CellProfiler/src/frontend/cellprofiler/gui/_tree_checkbox_dialog.py
imports: import wx
label_desc: Use image node_id 7 for calling the TreeCheckboxDialog obj's underlying member method code with example usage: obj.on_left_down(event) without return types