wasted margin space

the left & right margins are too wide, no matter if i choose Narrow, Medium or Wide; Byword wastes valuable screen real estate. is it possible to have the text wrap right at the edge of the window, instead of all that wasted space on either side?

latest version of Byword generates the following error:

"Byword" cant be opened because it is from an unidentified developer. Your security preferences allow installation of only apps from the Mac App Store and identified developers. Byword created this file today at 3:00 PM.

this happens when i use Byword to create a text document, save it to the Desktop as Byword.txt, then attempt to re-open it in Byword after changing the default Open with for the document to Byword, instead of TextEdit. if i launch Byword app by itself, no problem; but if i change the text document to Open with Byword (from the Get Info dialog), then i get the security warning above, and the document wont open.

theres always something like this with the Mac, never fails to disappoint me.

techcafe about Byword, v2.1