Makes selecting/activating view items (tree and grid view items) behave as wanted by the guidelines, consistent with many other editors: https://developer.blender.org/docs/features/interface/human_interface_guidelines/selection/#select-tweaking Noteworthy: - View items activate on press again, not on release - Pose library still only activates poses on click (releasing mouse before moving cursor), so dragging can be used to blend poses - New: Clicking on empty space in a view deselects all - Redundant activation in interface handlers code is removed Pull Request: https://projects.blender.org/blender/blender/pulls/146569