Thanks.
As of this evening, I nearly have all of the following ready, which means it's just about time to dive into gameplay:
void doSettings(void); //draw and interact the Settings dialog
void showAbout(void); //draw and pause on the About dialog
void drawDialog(char* title); //draw a DCS SmallWindow-style dialog box
void drawLine(int x1, int y1, int x2, int y2, int color); //integer-only Bresenham implementation
void fillArea(int x, int y, int width, int height, int color); //rectangular fill
int makeGray(int shade); //turn a shade into a gray color code
void plot(int x0, int y0, int color); //set point x0,y0 to color