Only show wrap guide when enough space

Previously the wrap guide would cause the
editor to scroll if the editor was narrower
than the wrap guide column without taking into
account whether any lines actually reach the guide.

Now the wrap guide only displays when either the wrap
guide column is less than the minimum width of the
editor layer or if the wrap guide column is less than
the entire width of the editor.

src/app/editor.coffee

@@ -759,6 +759,7 @@ class Editor extends View
       @underlayer.css('min-width', minWidth)
       @overlayer.css('min-width', minWidth)
       @layerMinWidth = minWidth
+      @trigger 'editor:min-width-changed'
 
   clearRenderedLines: ->
     @renderedLines.empty()

src/packages/wrap-guide/spec/wrap-guide-spec.coffee

@@ -10,6 +10,7 @@ describe "WrapGuide", ->
     rootView.attachToDom()
     editor = rootView.getActiveEditor()
     wrapGuide = rootView.find('.wrap-guide').view()
+    editor.width(editor.charWidth * wrapGuide.defaultColumn * 2)
 
   afterEach ->
     rootView.deactivate()
@@ -27,6 +28,7 @@ describe "WrapGuide", ->
       width = editor.charWidth * wrapGuide.defaultColumn
       expect(width).toBeGreaterThan(0)
       expect(wrapGuide.position().left).toBe(width)
+      expect(wrapGuide).toBeVisible()
 
   describe "when the font size changes", ->
     it "updates the wrap guide position", ->
@@ -34,6 +36,7 @@ describe "WrapGuide", ->
       expect(initial).toBeGreaterThan(0)
       rootView.trigger('window:increase-font-size')
       expect(wrapGuide.position().left).toBeGreaterThan(initial)
+      expect(wrapGuide).toBeVisible()
 
   describe "overriding getGuideColumn", ->
     it "invokes the callback with the editor path", ->
@@ -41,7 +44,7 @@ describe "WrapGuide", ->
       wrapGuide.getGuideColumn = (path) ->
         editorPath = path
         80
-      wrapGuide.updateGuide(editor)
+      wrapGuide.updateGuide()
       expect(editorPath).toBe(require.resolve('fixtures/sample.js'))
 
     it "invokes the callback with a default value", ->
@@ -51,7 +54,7 @@ describe "WrapGuide", ->
         column = defaultColumn
         defaultColumn
 
-      wrapGuide.updateGuide(editor)
+      wrapGuide.updateGuide()
       expect(column).toBeGreaterThan(0)
 
     # this is disabled because we no longer support passing config to an extension
@@ -68,5 +71,11 @@ describe "WrapGuide", ->
     it "hides the guide when the column is less than 1", ->
       wrapGuide.getGuideColumn = (path) ->
         -1
-      wrapGuide.updateGuide(editor)
+      wrapGuide.updateGuide()
+      expect(wrapGuide).toBeHidden()
+
+  describe "when no lines exceed the guide column and the editor width is smaller than the guide column position", ->
+    it "hides the guide", ->
+      editor.width(10)
+      wrapGuide.updateGuide()
       expect(wrapGuide).toBeHidden()

src/packages/wrap-guide/src/wrap-guide.coffee

@@ -1,4 +1,5 @@
 {View} = require 'space-pen'
+$ = require 'jquery'
 
 module.exports =
 class WrapGuide extends View
@@ -28,13 +29,18 @@ class WrapGuide extends View
     else
       @getGuideColumn = (path, defaultColumn) -> defaultColumn
 
-    @observeConfig 'editor.fontSize', => @updateGuide(@editor)
-    @subscribe @editor, 'editor-path-change', => @updateGuide(@editor)
-    @subscribe @editor, 'before-remove', => @rootView.off('.wrap-guide')
+    @observeConfig 'editor.fontSize', => @updateGuide()
+    @subscribe @editor, 'editor-path-change', => @updateGuide()
+    @subscribe @editor, 'editor:min-width-changed', => @updateGuide()
+    @subscribe $(window), 'resize', => @updateGuide()
 
-  updateGuide: (editor) ->
-    column = @getGuideColumn(editor.getPath(), @defaultColumn)
+  updateGuide: ->
+    column = @getGuideColumn(@editor.getPath(), @defaultColumn)
     if column > 0
-      @css('left', "#{editor.charWidth * column}px").show()
+      columnWidth = @editor.charWidth * column
+      if columnWidth < @editor.layerMinWidth or columnWidth < @editor.width()
+        @css('left', "#{columnWidth}px").show()
+      else
+        @hide()
     else
       @hide()