Glad an app like this exists - and for FREE

With some practice, I may be able to type efficiently with only my left hand, while keeping my right hand on my mouse. I have good dexterity with my left hand, so I sometimes type with just my left hand across the entire keyboard. This method may be more efficient (with some practice).

There seems to be a minor problem with the spelling auto-correction feature in OS X. When I get a “suggested spelling” choice at the cursor, I cannot press Space to accept the suggestion and move on. Pressing Space also does not add a space, until I get rid of the suggestion by doing something else. This problem does not occur if the "Correct spelling automatically" option is disabled (not checked) in System Preferences Keyboard pane Text tab.

NOTE: The "Enable access for assistive devices” setting (which must be enabled for this app) is in a different place in Yosemite’s System Preferences versus Mavericks and earlier (as described by the app). This setting is now in System Preferences Security & Privacy pane Privacy tab. Select Accessibility in sidebar. Check the box for Mirror-QWERTY (on the “Allow” list to the right). After changing setting, quit and re-open Mirror-QWERTY.

Another thing that confused me initially is that this app runs as a menu bar item. A small icon that looks like a circled “1” appears in the menu bar (on right side) when the app is running. The mirroring feature is always active while the app is running, which can cause mis-typed letters if I switch to typing with both hands while the app is running (pressing letter key too quickly after Space). Click the app’s menu bar icon to access the app’s options and quit app. The app does not appear in the Dock.

ken1w about Mirror-QWERTY: One-Hand Typing