- id maps are not editable
- handle exceptions thrown by the file reader
- texts are always above the edges
- store a default value for all maps, so that edges and nodes created after
adding a new map receive the default value too
- create node on button release, not on click (fixes a few oddities)

p max 10 17

n 2 s

n 9 t

a 1 2 20

a 1 3 0

a 2 2 3

a 2 3 8

a 2 4 8

a 3 6 5

a 4 3 5

a 4 6 5

a 4 7 5

a 5 4 3

a 6 8 3

a 6 7 10

a 6 9 10

a 7 9 8

a 9 10 20

a 9 2 5

a 10 6 5