This dialog is available from the Graphs / Options / Overlaid Investments... menu command.
This dialog box allows you to select the investments that will be overlaid for these graph types:
Investment Overlay - Share Price
Highlight the investments to overlay from the list.
Choose which of the overlaid investments will be in the "Scrolling Position". When viewing an "Overlay" graph type you may also use the arrow and page up/down keys, as well as their equivalents on the toolbar, to scroll through which investments are overlaid. The investment in the "scrolling position" (this is also the investment on the left-most side of the legend) will be scrolled to the next/prior displayed investment. This operation skips over other investments already selected for overlay. This feature is particularly useful if you have some investments (like the S&P 500 and the Dow for example) that you would like to compare to all the other investments in your portfolio. Using this feature you can quickly scroll through each investment, comparing it against the latter investments selected for overlay.
To overlay investments from other portfolios besides the currently active portfolio, select the "Show Investments From all Portfolios" option. The "Clear All" button deselects all investments.
This dialog box selects which investments to overlay. To actually overlay the investments you must select one of the "Overlay" graph types from the Graphs menu.
Selecting Portfolios to Overlay