Hi,
I love the look of an additional window trim color with your color scheme -- that's a wonderful choice.

Here are a few paint colors to sample for the inner window trim that could work with your current colors.

Benjamin Moore Knoxville Gray HC-160
http://www.myperfectcolor.com/en/color/5971_Benjamin-Moore-HC-160-Knoxville-Gray

Benjamin Moore Steamed Spinach 643
http://www.myperfectcolor.com/en/color/5586_Benjamin-Moore-643-Steamed-Spinach

Benjamin Moore Martha's Vineyard 630
http://www.myperfectcolor.com/en/color/5573_Benjamin-Moore-630-Marthas-Vineyard

Benjamin Moore Old Glory 811
http://www.myperfectcolor.com/en/color/5748_Benjamin-Moore-811-Old-Glory

Because you already have warm and bright colors in the color scheme, I've suggested deeper and cooler colors to balance things out, and add a pop of color.

Hope this helps!

Diana