bling bling tag preview cut off image

i just got the feeling that this is not how it should look, at all.

for bling i'm using the latest commit to master.

the code of the task preview widget i used:

bling.widget.task_preview.enable {
    height = 200,              -- The height of the popup
    width = 300,               -- The width of the popup
    placement_fn = function(c) -- Place the widget using awful.placement (this overrides x & y)
        awful.placement.top(c, {
            margins = {
                top = 30
            }
        })
    end
}

the code of the tasklist itself:

    -- Create a tasklist widget
    s.mytasklist = awful.widget.tasklist {
        screen  = s,
        filter  = awful.widget.tasklist.filter.currenttags,
        buttons = tasklist_buttons,
        style = { 
            shape = function(cr, width, height) gears.shape.rectangle(cr, width, height, height/4) end,
            },
        layout   = {
            spacing = 5,
            layout  = wibox.layout.fixed.horizontal
        },
        widget_template = {
            {
                {
                    {
                        id     = 'clienticon',
                        widget = awful.widget.clienticon,
                    },
                    left = 6,
                    right = 6,
                    top = 1,
                    bottom = 1,
                    widget  = wibox.container.margin
                },
                id            = 'background_role',
                widget        = wibox.container.background,
            },
            create_callback = function(self, c, index, objects) --luacheck: no unused args
                self:get_children_by_id('clienticon')[1].client = c

                -- BLING: Toggle the popup on hover and disable it off hover
                self:connect_signal('mouse::enter', function()
                        awesome.emit_signal("bling::task_preview::visibility", s,
                                            true, c)
                    end)
                    self:connect_signal('mouse::leave', function()
                        awesome.emit_signal("bling::task_preview::visibility", s,
                                            false, c)
                    end)
            end,
            layout = wibox.layout.align.vertical,
        },
    }

any idea where did i screw up?