Dramatically improve reliability of clicking (and drag+drop).

In lieu of a gnarly hack, Scoot is brought to the background *before* any
mouse-related operation (like a click) is issued. This way, if the target
window was focused before Scoot was invoked, the target window will regain
focus ahead of the mouse-related operation.

Closes #28.

Scoot/KeyboardInputWindow+Keyboard.swift

@@ -60,17 +60,16 @@ extension KeyboardInputWindow {
         }
 
         switch (character, isHoldingDownLeftMouseButton, modifiers) {
+        // Scoot is brought to the background before issuing any mouse-related
+        // operation (like clicking). If the target window was focused ahead of
+        // invoking Scoot, it will regain focus _before_ clicking, which
+        // significantly improves reliability. For more context, see
+        // <https://github.com/mjrusso/scoot/issues/28>.
         case ("\r", false, []):
+            appDelegate?.bringToBackground()
             mouse.click(button: .left)
             return
         case ("\r", false, _), ("[", false, _), ("]", false, _):
-            // The user is pressing the left mouse button while holding down
-            // one or more modifier keys, or pressing the middle or right mouse
-            // button (with or without modifiers). In any of these cases, a
-            // system-provided context menu will likely pop up. Scoot can't
-            // take control of the mouse cursor when a context menu is active,
-            // so it is a better user experience to bring Scoot to the
-            // background before issuing the click.
             appDelegate?.bringToBackground()
 
             // Note that if a modifier is being held, it will "pass through" to
@@ -87,15 +86,21 @@ extension KeyboardInputWindow {
             }
             return
         case ("\r", true, _):
+            appDelegate?.bringToBackground()
             mouse.notifyDrag(.left)
             mouse.release(.left)
             isHoldingDownLeftMouseButton = false
             return
         case ("=", false, _):
+            appDelegate?.bringToBackground()
             mouse.pressDown(.left)
             isHoldingDownLeftMouseButton = true
+            // Automatically bring Scoot to the foreground, so the user can
+            // continue their drag operation.
+            appDelegate?.bringToForeground()
             return
         case ("\\", false, _):
+            appDelegate?.bringToBackground()
             mouse.doubleClick(button: .left)
             return
         default:

Scoot/Mouse.swift

@@ -37,33 +37,8 @@ struct Mouse {
     }
 
     func click(button: Mouse.Button) {
-        // It should be possible to `pressDown()` and then `release()` (after a
-        // short delay), however that approach doesn't work reliably: in some
-        // applications (for example, when trying to click on a hyperlink in a
-        // browser, or in an apps that render their user interface using web
-        // technologies), mouse clicks don't actually register.
-        //
-        // For an unknown reason, posting two `leftMouseDown` events, followed
-        // by a single `leftMouseUp`, *seems* to work consistently everywhere.
-        // How's that for a hack?
-        //
-        // [N.B.: A previous implementation issued two clicks in a row (i.e.,
-        // `pressDown()`, `release()`, `pressDown()`, `release()`), and that
-        // worked better than one could reasonably expect. However, there were
-        // rare cases where two clicks would actually be registered: for example,
-        // in Safari, clicking the "close tab" button (the one embedded in the
-        // tab itself) would result in two tabs being closed. Another example:
-        // it wasn't possible to use Scoot to bring up it's menu bar: two clicks
-        // would register, and it would immediately close.]
-        //
-        // [N.B.: This question [0] on Stack Overflow ("Simulating mouse clicks
-        // on Mac OS X does not work for some applications") seems relevant, but
-        // unfortunately none of the proposed strategies seem to work.]
-        //
-        // [0]: https://stackoverflow.com/q/2369806/15304124
         pressDown(button)
-        pressDown(button)
-        usleep(40000)
+        usleep(10000)
         release(button)
     }