title: TreeView option to select and de-select by clicking?
body: <p>I have been looking for a treeView widget option where I can select only a single row at a time by clicking it and then de-select it by clicking on it again. I found how to make it so that you can select only one row at a time, but I was unable to find an option that allowed u to click the selected row to de-select it. </p>
  
  <p>Does anyone know how this can be done? Any help would be appreciated.</p>