Better context checking for toolbar buttons

[Frederico Caldeira Knabben]

There is room the enhance the context checking we do for several toolbar buttons. While the current approach is correct, it can be optimized to better fit user's intentions, helping on the UI usability.

One good example for that is related to object selections. There is no much sense on having inline styles, like bold, enabled when an image is selected.

Let's open a discussion and analise all possible cases first.