Add comment explaining motivation for didPaste implemenation

src/text-editor-component.js

@@ -1553,7 +1553,12 @@ class TextEditorComponent {
   }
 
   didPaste (event) {
-    // TODO Explain the motivation for this logic
+    // On Linux, Chromium translates a middle-button mouse click into a
+    // mousedown event *and* a paste event. Since Atom supports the middle mouse
+    // click as a way of closing a tab, we only want the mousedown event, not
+    // the paste event. And since we don't use the `paste` event for any
+    // behavior in Atom, we can no-op the event to eliminate this issue.
+    // See https://github.com/atom/atom/pull/15183#issue-248432413.
     if (this.getPlatform() === 'linux') event.preventDefault()
   }