Clicking on empty space shows context menu

[Nodd]

Clicking on an empty space in the list view displays a context menu (for both right and left click), while it should just hide the current context menu and never open a new one. The contrext menu should be opened on a package line exclusively.

[Nodd]

When showing updatable packages only, it's common to have an empty space.

[Nodd]

The context menu for left click is shown only if the check colomn was left-clicked first.