The mouse button callback will return true when all three conditions are met:
1. This TreeView is "enabled" (see nanogui.Widget.mEnabled).
2. p is inside this TreeView.
3. button is MouseButton.Left.
Since a mouse button event is issued for both when the mouse is pressed, as well
as released, this function sets nanogui.TreeView.mPushed to true when
parameter down == true. When the second event (down == false) is fired,
nanogui.TreeView.mChecked is inverted and nanogui.TreeView.mCallback
is called.
That is, the callback provided is only called when the mouse button is released,
**and** the click location remains within the TreeView boundaries. If the user
clicks on the TreeView and releases away from the bounds of the TreeView,
nanogui.TreeView.mPushed is simply set back to false.
The mouse button callback will return true when all three conditions are met:
1. This TreeView is "enabled" (see nanogui.Widget.mEnabled). 2. p is inside this TreeView. 3. button is MouseButton.Left.
Since a mouse button event is issued for both when the mouse is pressed, as well as released, this function sets nanogui.TreeView.mPushed to true when parameter down == true. When the second event (down == false) is fired, nanogui.TreeView.mChecked is inverted and nanogui.TreeView.mCallback is called.
That is, the callback provided is only called when the mouse button is released, **and** the click location remains within the TreeView boundaries. If the user clicks on the TreeView and releases away from the bounds of the TreeView, nanogui.TreeView.mPushed is simply set back to false.