gr: use correct aspect ratio (fixes #1219)

src/backends/gr.jl

@@ -412,6 +412,9 @@ function gr_viewport_from_bbox(sp::Subplot{GRBackend}, bb::BoundingBox, w, h, vi
         viewport[3] = 0.5 * (vp[3] + vp[4] - extent)
         viewport[4] = 0.5 * (vp[3] + vp[4] + extent)
     end
+    if hascolorbar(sp)
+        viewport[2] -= (viewport[2] - viewport[1]) * 0.1
+    end
     viewport
 end
 
@@ -687,11 +690,6 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
         end
     end
 
-    if cmap
-        # note: add extra midpadding on the right for the colorbar
-        viewport_plotarea[2] -= 0.1
-    end
-
     # set our plot area view
     gr_set_viewport_plotarea()