Tags selector should be possible to maximize by dragging up

[kirillt]

There is a "tags selector" in resources grid. It should be possible to maximize it by dragging its edge up.

In maximized state, a user still can select tags but resources grid is not visible, hence not necessary to update previews. But the user should receive feedback about his actions, so number of resources selected should be displayed.

[kirillt]

Implemented in ARK-Builders/ARK-Navigator#28

Previews are still get updated upon tags selection modified, but so far it doesn't look like a real problem.