From a72dc17b87f0dfabdd5db8ff8289104ac019084f Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Tue, 31 Jan 2012 11:21:08 -0700
Subject: [PATCH] Move hidden input to follow cursor to stop spurious scrolling

Commit 8e77c05c fixed scrolling *up* when clicking the buffer while
scrolled down. But it was still scrolling to the far left when typing /
clicking on a really long line. This commit solves both issues by
always positioning the hidden input to the same location as the cursor,
so it doesn't tell webkit to scroll away from the current focus when it
is focused or the user types.
---
 spec/atom/editor-spec.coffee | 7 ++++++-
 src/atom/editor.coffee       | 5 ++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/spec/atom/editor-spec.coffee b/spec/atom/editor-spec.coffee
index c4d6f2790..d28c18521 100644
--- a/spec/atom/editor-spec.coffee
+++ b/spec/atom/editor-spec.coffee
@@ -50,13 +50,18 @@ describe "Editor", ->
 
   describe "cursor movement", ->
     describe ".setCursorPosition({row, column})", ->
-      it "moves the cursor to cover the character at the given row and column", ->
+      beforeEach ->
         editor.attachToDom()
         editor.setCursorPosition(row: 2, column: 2)
 
+      it "moves the cursor to cover the character at the given row and column", ->
         expect(editor.getCursor().position().top).toBe(2 * editor.lineHeight)
         expect(editor.getCursor().position().left).toBe(2 * editor.charWidth)
 
+      it "moves the hidden input element to the position of the cursor to prevent scrolling misbehavior", ->
+        expect(editor.hiddenInput.position().top).toBe(2 * editor.lineHeight)
+        expect(editor.hiddenInput.position().left).toBe(2 * editor.charWidth)
+
     describe "when the arrow keys are pressed", ->
       it "moves the cursor by a single row/column", ->
         editor.trigger keydownEvent('right')
diff --git a/src/atom/editor.coffee b/src/atom/editor.coffee
index be207d0e9..5ef8f7756 100644
--- a/src/atom/editor.coffee
+++ b/src/atom/editor.coffee
@@ -66,7 +66,6 @@ class Editor extends Template
 
     handleEvents: ->
       @on 'focus', =>
-        @hiddenInput.css(top: @scrollTop())
         @hiddenInput.focus()
         false
 
@@ -79,8 +78,12 @@ class Editor extends Template
       @hiddenInput.on "textInput", (e) =>
         @insertText(e.originalEvent.data)
 
+      @on 'cursor:position-changed', =>
+        @hiddenInput.css(@pixelPositionFromPoint(@cursor.getPosition()))
+
       @one 'attach', =>
         @calculateDimensions()
+        @hiddenInput.width(@charWidth)
         @focus()
 
     buildLineElement: (lineText) ->