FT Portfolio Charts

Setting up a portfolio on FT.com (see previous article) allows you to plot your portfolio performance, and compare it to a number of market index benchmarks. Here's the performance of a portfolio of 6 UK stocks compared to the FTSE 100:



However, the only way I've found to do this seems unnecessarily convoluted. The FT portfolio service allows you to enter stock and cash transactions, but I can find no way to fund a portfolio with cash, and then have subsequent share purchases reduce the cash total. Instead, when entering a share purchase, I have to enter a corresponding cash debit.

Am I being a dolt? Or could this be made more user-friendly?