That was already given where China was controlling Tibet and India was controlling Sikkim. All they did sign was you consider Tibet to be part of China and Sikkim will be part of India. There was no deal besides how you guy's need to perceive from know on.
China and India controlled Tibet and Sikkim respectively, but the status/fate of those areas are uncertain. That is the reason why both China and India decide to go through with this deal of recognition of each others territory. By doing so enables them to settle the status and formalize the border in that area to the world.
If they did not do this, the situation would lead to what is happening now in Kashmir between India and Pakistan, a disputed territory regardless of control with no solution in sight. By doing this deal, it is in the interest of both China and India to put the Tibet/Sikkim issue behind them.
The problem is that China does not control Arunachal Pradesh. They can claim anything they want. The only way they will get Arunachal Pradesh is attacking Inida, which will start war. Which I believe China will not start, hense they are just doing this to keep India on there toes and distracted.
China does not control and they are only claiming it. The Chinese cannot claim anything they want. They can only claim for territory that has a historical/legal bases for their reasoning. Whether they can claim it is another matter. Nonetheless, they have the right to claim.
That is true about getting Arunachal Pradesh through war because I don't see India giving the territory to China willingly for nothing. With that said, China will not start war as this would be a big blow to her rapid rise both economically and politically. So mostly, China is using this issue as a card to use on India in future strategic discussions.
And if you study China really well, they are appling the same strategy towards Taiwan regarding America. They just keep claiming it, but they know to get it they have to start a War.
The Taiwan situation is incomparable because of the fact that we don't own/control Taiwan. We are treating Taiwan as a foreign entity and will protect Taiwan should the Chinese attack.
The Chinese has the right to claim Taiwan because the island historically is part of China. Yes, Taiwan is ruled separately, but the island and the mainland are one entity. The best comparison for this is to Pakistan and East Pakistan (Bangladesh). They were one entity, the only difference here is that Taiwan would have little to none chance of emulating what Bangladesh did (Independence).
There is only two ways for Taiwan to become independent and that is peacefully (politically) or aggressively (militarily). Politically, the chance is slim as most of the world and major nations oppose this idea. We have already made it clear to the Taiwanese that we do not support independence.
Militarily, Taiwan stands no chance against China should she start war on the mainland. This is because they know that the US will say "bye bye" when Taiwan attacks first. Our policy is only defend Taiwan being attacked and not defend them should they suicidally attack the mainland. Since the Chinese are not attacking, we are kept at bay.
That is why Taiwan is in this limbo situation, they can't be independent politically and they can't through militarily.
In regards, to getting Taiwan, the Chinese are just waiting for time to resolve this diplomatically. Because they know through militarily, they would face the US.