SGScript | coroutine-based simple dialog system

function draw_question( question, answers )
{
    x = 64;
    y = 400;
    sel = null;
    for(;;)
    {
        height = 64 + dict_size( answers ) * 24;
        SS_DrawColorRect_WH( x, y, 400, height, 0, 0, 0, 0.5 );
        SS_DrawTextLine( question, Font, x, y, color(1,1,1) );

        i = 0;
        mon = null;
        selfunc = null;
        foreach( func, name : answers )
        {
            ay = y + 64 + i * 24;
            mouseon = mpos.x >= x && mpos.x < x + 400 && mpos.y >= ay && mpos.y < ay + 24;
            if( mouseon )
                mon = i;
            issel = i === sel;
            if( issel )
                selfunc = func;
            SS_DrawColorRect_WH( x, ay, 400, 24, mouseon - issel * 0.5, 0, 0, 0.5 );
            SS_DrawTextLine_VC( name, Font, x, ay + 12, color(1) );
            i++;
        }

        if( curclick && !prevclick )
            sel = mon;
        else if( !curclick && prevclick )
        {
            if( sel !== null && mon === sel )
            {
                thread _G[ "q_" $ selfunc ]();
                return;
            }
            sel = null;
        }

        yield;
    }
}

function q_step0(){ draw_question( "why not?", { "step1" = "Well, let me think about it", "step0" = "No reason" } ); }
function q_step1(){ draw_question( "shall we proceed?", { "step2" = "Yes", "step0" = "No", "info" = "Tell me more" } ); }
function q_info(){ draw_question( "This is a test dialog", { "step1" = "Ok, got it" } ); }
function q_step2(){ draw_question( "what should we do?", { "action1" = "Let's do the action 1", "action2" = "Let's do the action 2", "step1" = "Let's take a step back" } ); }
function q_action1(){ draw_question( "Action 1 done!", { "step2" = "Ok!" } ); }
function q_action2(){ draw_question( "Action 2 done!", { "step2" = "Ok!" } ); }

// started with "thread q_step1();"