I've realized a slight downside to the gradiation in eavesdropping - I can't really rely on the game remembering what info the player has learned. It wouldn't be fair if you see a word like m_rd_r; and then are not given the option to inform your superior about the murder plot when it's obvious to the player what that word is. Similarly, if you only saw ___d__ and then WERE given that option, you would wonder why. That may be OK for the game I'm making, but another example of something that is really simple to build initially but increases complexity by several factors.
Being able to move around during conversation is another one of these "features". It's actually easier to allow the player to move during dialog than not. But those constraints are a standard in most games for a reason. They cut down on bugs and the possibilities for the player to attempt to do things that the designer did not factor into their creation.
Older games often had less well-defined restrictions for the player. Sometimes this made for some very cruel situations. There are many situations in the King's Quest games where the player can do something wrong, or miss something that they need and cross over to a new area they cannot escape from, and be stuck with no way to find a solution anymore. One example is in King's Quest 5, you get a pie very early on, that you are allowed to eat. But you need this pie later, so if you eat it, you cannot complete the game. Most modern games attempt to make these sorts of things impossible.
I want to allow them as much as possible - but without allowing the players early decisions to prevent the game from being completed. It just may not be the most satisfactory ending.
But in loosening constraints, even just a little, the potential for bugs, confusing situations, and players getting frustrated because they try something that SHOULD work but does not, increases. As I take a second look at this project I may want to add some constraints back in. It's a difficult balance indeed.
Oh, I should write an actual dev update... I added the fading back to dialog so that once you are outside of even eavesdropping range the text actually goes away.