Not out of the box to my knowledge.
It's one of the drawbacks with blocks as I see it. To edit a block on a page takes a little longer, while being more flexible, so keeping a healthy ratio between blocks and normal on-page properties is good.
Since a block, shared one that is, is used on many pages I guess it's a design decision from episerver as well. As an editor you want to know if you are editing a normal page property, which will normally only update that page, or a block which might be used on several pages.
It's probably possible to implement with some overrides to contentarea renderer and publish event. I don't recall seeing anyone doing it yet though :)
Yeah, I understand that it would be wierd to change a block on one page, which affects other pages too. Still, I could live with that. If anyone has solved this, please share your thoughts!
Also, I'm a developer, so if anyone could point me in the right direction, that would be incredibly helpful!
Lets say I have a page that has a content area and other content properties. In this content area, there's a block which only contains an wysiwyg (XHtmlString). While editing the page, can I directly edit the blocks wysiwyg?