title: Python Bokeh Bar Chart - Modify Legend Box
body: <p>I am creating a bar chart using Bokeh.Charts.Bar. My problem is that, I have a legend box of 15 labels, and this legend box is covering the right most column (I am using legend='top-right', it would be the same if I change it to 'top-left', it would cover the left most column). So I am trying to create a legend object (bokeh.models.annotations.legend) to set background_fill_data = 0, label_standoff, legend_pedding etc. in order to move the legend box around or make it transparent so that it is easier to create the chart. However, I have achieved nothing so far. Help is really appreciated. Thanks. </p>
  
  <pre><code>bar = Bar(result_df, values='Value', label='Label', legend='bottom_right',
                    stack='Stack', title="Title", bar_width=0.4,
                    color=color(columns='Stack', palette=self.get_colors(5), tools="pan,wheel_zoom,box_zoom,reset,resize,hover")
          hover = bar.select(dict(type=HoverTool))
          hover.tooltips=[("Stack", "@Stack"), (field_name, "@height{" + tooltip_fmt + "}")]
  
  
  legend = Legend({
                "background_fill_alpha": {
                  "value": 0
                },
                "background_fill_color": {
                  "value": "#ffffff"
                },
                "border_line_alpha": {
                  "value": 1.0
                },
                "border_line_cap": "butt",
                "border_line_color": {
                  "value": "black"
                },
                "border_line_dash": [],
                "border_line_dash_offset": 0,
                "border_line_join": "miter",
                "border_line_width": {
                  "value": 1
                },
                "glyph_height": 20,
                "glyph_width": 20,
                "label_height": 20,
                "label_standoff": 15,
                "label_text_align": "left",
                "label_text_alpha": {
                  "value": 1.0
                },
                "label_text_baseline": "middle",
                "label_text_color": {
                  "value": "#444444"
                },
                "label_text_font": "helvetica",
                "label_text_font_size": {
                  "value": "10pt"
                },
                "label_text_font_style": "normal",
                "label_width": 50,
                "legend_padding": 10,
                "legend_spacing": 3,
                "legends": [],
                "level": "annotation",
                "location": "top_right"
              })
  bar.add_legend(legend)
  </code></pre>