When editing a dashboard the edit window does not fully display and does not provide a vertical or horizontal scroll bar.
The dashboard edit window by design, does not display a scroll bar. The problem is caused when the browser is Zoomed.
Setting the Browser Zoom setting back to 100% will correct this.
The Browser Zoom settings can be found using the following:
Chrome-Tool bar found in the upper right corner.
Firefox- Tool bar found in the upper right corner.
IE- Under the View menu>Zoom> % settings.
Safari- Under the View menu>Zoom settings.