How can I use an array as map value?

You can't copy arrays by value like that.

Here are several solutions, but I recommend #4 for your needs:

1. Use an std::vector instead of an array.

2. Use a map of pointers to arrays of 3 elements:

   int red[3]   = {1,0,0};
   int green[3] = {0,1,0};
   int blue[3]  = {0,0,1};
   std::map<int,int(*)[3]> colours;
   colours.insert(std::pair<int,int(*)[3]>(GLUT_LEFT_BUTTON,&red));
   colours.insert(std::pair<int,int(*)[3]>(GLUT_MIDDLE_BUTTON,&blue));
   colours.insert(std::pair<int,int(*)[3]>(GLUT_RIGHT_BUTTON,&green));
   // Watch out for scope here, you may need to create the arrays on the heap.
   

3. Use boost tuples instead of arrays of 3 elements.

4. Instead of using an array make a new struct that takes 3 elements. Make the map<int, newstructtype>. Or wrap your array in a struct as follows:

   struct Triple
   {
       int color[3];
   };
   
   // Later in code
   Triple red = {1, 0, 0}, green = {0, 1, 0}, blue = {0, 0, 1};
   std::map<int,Triple> colours;
   colours.insert(std::pair<int,Triple>(GLUT_LEFT_BUTTON,red));
   colours.insert(std::pair<int,Triple>(GLUT_MIDDLE_BUTTON,blue));
   colours.insert(std::pair<int,Triple>(GLUT_RIGHT_BUTTON,green));
   

Arrays are not first class constructs in C++. They are not Copy Constructible nor Assignable which are requirements for values of std::map. You can use boost::array or std::vector.

Use std::tr1::array.

typedef std::tr1::array<int, 3> Triple;
Triple red   = {1, 0, 0};
Triple green = {0, 1, 0};
Triple blue  = {0, 0, 1};
std::map<int, Triple> colours;
colours.insert(std::make_pair(GLUT_LEFT_BUTTON,   red));
colours.insert(std::make_pair(GLUT_MIDDLE_BUTTON, blue));
colours.insert(std::make_pair(GLUT_RIGHT_BUTTON,  green));

Or std::array in C++11 and above

using  Triple = std::array<int, 3>; 
Triple red   = {1, 0, 0};
Triple green = {0, 1, 0};
Triple blue  = {0, 0, 1};
std::map<int, Triple> colours;
colours.insert(std::make_pair(GLUT_LEFT_BUTTON,   red));
colours.insert(std::make_pair(GLUT_MIDDLE_BUTTON, blue));
colours.insert(std::make_pair(GLUT_RIGHT_BUTTON,  green));

Don't map to an int[], instead, map to an int* like this:

#include <iostream>
#include <map>
using namespace std;
int main(){
    std::map<int,int*> colors;
    int red[] = {3,7,9};
    colors[52] = red;
    cout << colors[52][1];  //prints 7
    colors[52][1] = 11;
    cout << colors[52][1];  //prints 11
    return 0;
}