Well instead of opening a brand new topic and creating another topic… 
Idea name: Modular taxiway markings
Example picture:
Description;
So there will be 2 major parts of this feature; Tile coloring and writing.
Tile coloring: 1 tile of taxiways, runways, tarmac and stands (a.k.a.1 small square on game) will be paintable with various colors on aviation. Yellow, red, blue, green, black (for concrete background) or gray (for asphalt background). When user paints 2 tiles next to each other; tile colors will be connected and it will be seen as 1 colored rectangular area.
Writing: User can write things on taxiways, runways, tarmac and stands. Each character will cover
1 small tile. Players will be able to select colors AND some special symbols like arrows from a dropdown menu. There won’t be a strain to have a colored background for writings. Players can just go and write whatever they want on default taxiways, runways, tarmac and stands.
Arrow examples: Unicode: Arrows →