Manually set rows per page in the model

spec/text-editor-presenter-spec.coffee

@@ -2026,6 +2026,20 @@ describe "TextEditorPresenter", ->
               }
 
     describe ".height", ->
+      it "updates model's rows per page when it changes", ->
+        presenter = buildPresenter(explicitHeight: 50, lineHeightInPixels: 10, horizontalScrollbarHeight: 10)
+
+        presenter.getState() # trigger state update
+        expect(editor.getRowsPerPage()).toBe(4)
+
+        presenter.setExplicitHeight(100)
+        presenter.getState() # trigger state update
+        expect(editor.getRowsPerPage()).toBe(9)
+
+        presenter.setHorizontalScrollbarHeight(0)
+        presenter.getState() # trigger state update
+        expect(editor.getRowsPerPage()).toBe(10)
+
       it "tracks the computed content height if ::autoHeight is true so the editor auto-expands vertically", ->
         presenter = buildPresenter(explicitHeight: null, autoHeight: true)
         expect(presenter.getState().height).toBe editor.getScreenLineCount() * 10

spec/text-editor-spec.coffee

@@ -4365,8 +4365,8 @@ describe "TextEditor", ->
 
   describe ".pageUp/Down()", ->
     it "moves the cursor down one page length", ->
-      editor.setLineHeightInPixels(10)
+      editor.setRowsPerPage(5)
-      editor.setHeight(50, true)
+
       expect(editor.getCursorBufferPosition().row).toBe 0
 
       editor.pageDown()
@@ -4383,8 +4383,8 @@ describe "TextEditor", ->
 
   describe ".selectPageUp/Down()", ->
     it "selects one screen height of text up or down", ->
-      editor.setLineHeightInPixels(10)
+      editor.setRowsPerPage(5)
-      editor.setHeight(50, true)
+
       expect(editor.getCursorBufferPosition().row).toBe 0
 
       editor.selectPageDown()

src/text-editor-presenter.coffee

@@ -688,6 +688,7 @@ class TextEditorPresenter
 
     clientHeight = @height - @horizontalScrollbarHeight
     @model.setHeight(clientHeight, true)
+    @model.setRowsPerPage(Math.floor(clientHeight / @lineHeight))
 
     unless @clientHeight is clientHeight
       @clientHeight = clientHeight

src/text-editor.coffee

@@ -2895,7 +2895,9 @@ class TextEditor extends Model
 
   # Returns the number of rows per page
   getRowsPerPage: ->
-    Math.max(1, Math.floor(@getHeight() / @getLineHeightInPixels()))
+    Math.max(@rowsPerPage ? 1, 1)
+
+  setRowsPerPage: (@rowsPerPage) ->
 
   ###
   Section: Config