No you're missing the meaning of these words.
* "All" means every window
* "current" is the window you are playing.
* "w/ current" means with, or "including", the current window
* "w/o current" means without, or "excluding", the current window
Does this mean signal keystroke is only sent to the window that can understand the keystroke/ binding?
There's an input keystroke (which you press), and an output keystroke (which ISBoxer sends to the game). These are referred to as [url]http://isboxer.com/wiki/Hotkey]Hotkey[/url] and Key Combination.
Any time you set up a Hotkey in ISBoxer, such as with a Mapped Key, that Hotkey will not be passed to the game -- it's an ISBoxer Hotkey. If you want the Hotkey to be passed to the game from a Mapped Ky, that must be defined as part of the mapping. What gets sent to the game does not need to be (and most typically is not) the same key(s) you pressed.
If you set up a Mapped Key, with the Hotkey F1, which has a
Keystroke Action that sends F1 to "All w/o Current", then every window except the current window is going to receive F1. If that sends F2 to "All w/ Current" instead, then when you press F1 it is going to send F2 to every window, including the current window, and no windows receive F1 -- because it wasn't mapped to do so.