Altium schematic rectangle color?
You can make the rectangles any color you want, with any color border you want and any of several (four) border width selections. See below (dialog from Properties): 

There are 256 colors available, with selectable swatches, including 16 custom colors that you can specify in 8-bit per color RGB or 8-bit per parameter HSL (Hue-Saturation-Luminance) format.