GameMaker Inventory/spell system Help

[Smallmak]

Hello, I am working on creating an inventory system/spell system where players can drag their skills or items into 1 of 12 slots slots 1-3 are mouse buttons while the rest would correspond to number pad buttons. here is what I have so far

Create event ("tal" standing for "talents" or "spells");

depth = -1;
scale = 2;
showTalents = false;

talSlots = 9
talRows = 6;
talColumns = 8;

selected_tal = 0;
pickedUpTalent = -1;
m_slotx = 0;
m_sloty = 0;

x_buffer = 3;
y_buffer = 3;




cellSize = 32;
tal_UI_width = sprite_get_width(sprite5)-32;
tal_UI_height = sprite_get_height(sprite5) -32;

spr_tal_UI = sprite5;
spr_tal_columns = sprite_get_width(sprite6)/cellSize;
spr_tal_rows = sprite_get_height(sprite6)/cellSize;


gui_width = display_get_gui_width();
gui_height = display_get_gui_height()
tal_UI_x = (gui_width/2)-(tal_UI_width/2 * scale);
tal_UI_y =(gui_height/2)-(tal_UI_height/2 * scale);

slotsX = tal_UI_x +(4*scale);
slotsY = tal_UI_y +(3*scale);


ds_Tal = ds_grid_create(1,talSlots);

ds_Tal[# 0, 0] = 1;
ds_Tal[# 0, 1] = 2;
ds_Tal[# 0, 2] = 3;
ds_Tal[# 0, 3] = 0;
ds_Tal[# 0, 4] = 0;
ds_Tal[# 0, 5] = 2;
ds_Tal[# 0, 6] = 0;
ds_Tal[# 0, 7] = 0;
ds_Tal[# 0, 8] = 2;

under the step event I have this

if(keyboard_check_pressed(ord("T"))){ showTalents = !showTalents};

if(!showTalents) exit;
#region MOUSE IN TALENT MENU

mousex = device_mouse_x_to_gui(0);
mousey = device_mouse_y_to_gui(0);

var cell_xbuff = (cellSize+x_buffer)*scale;
var cell_ybuff = (cellSize+y_buffer)*scale;

var i_mousex = mousex - slotsX;
var i_mousey = mousey - slotsY;


var nx = i_mousex div cell_xbuff;
var ny = i_mousey div cell_ybuff;

var mouse_in_tal = true;
if(nx >= 0 and nx < talColumns and ny >=0 and ny < talRows ){
   var sx = i_mousex - (nx*cell_xbuff) ;
   var sy = i_mousey - (ny*cell_ybuff) ;
  
   if(sx < cellSize*scale and sy < cellSize*scale){
   m_slotx = nx;
   m_sloty =ny;
       }
   }else{mouse_in_tal = false;}
  
selected_tal = min(talSlots -1, m_slotx + (m_sloty * talColumns));
#endregion




if(pickedUpTalent != -1){
  
   }


if(mouse_check_button(mb_right)) {
       pickedUpTalent = selected_tal;
   }

and under the draw GUI event i have this

if(!showTalents) exit;


   var c = c_white;
   draw_sprite_part_ext(sprite5,0,cellSize,0,tal_UI_width,tal_UI_height,tal_UI_x,tal_UI_y,scale,scale, c,1)

var ii, ix, iy, xx, yy, sx, sy, sTalent, tal_grid,
ii = 0; ix = 0; iy = 0; xx = 0; yy = 0; sTalent = 0; tal_grid = ds_Tal
repeat(talSlots){
       xx = slotsX + ((cellSize+x_buffer) * ix * scale);
       yy = slotsY + ((cellSize+y_buffer) * iy * scale);
   //x,y,location
   sTalent = ds_Tal[# 0, ii]
   sx = (sTalent mod talColumns) *cellSize;
   sy = (sTalent div talColumns) *cellSize;
  
   draw_sprite_part_ext(
           sprite6, 0, sx, sy, cellSize,cellSize,
           xx,yy, scale,  scale, c_white,1);
          
   switch(ii){
   case selected_tal:
       if(sTalent > 0){
           gpu_set_blendmode(bm_add);
           draw_sprite_part_ext(sprite6,0,sx,sy,cellSize,cellSize,xx,yy,
           scale,scale,c_white,0.5);  
           gpu_set_blendmode(bm_normal);
      
        break; }
  
   case pickedUpTalent : if(sTalent > 0) draw_sprite_part_ext(
           sprite6, 0, sx, sy, cellSize,cellSize,
           xx,yy, scale,  scale, c_white, 0.2
       );
      
        break;
  
  
   }
  
  

   ii += 1;
   ix = ii mod talColumns;
   iy = ii div talColumns;
  
   }
if (pickedUpTalent != -1){
//Item
   sTalent = ds_Tal[# 0, pickedUpTalent];
   sx = (sTalent mod spr_tal_columns)*cellSize;
   sy = (sTalent div spr_tal_columns)*cellSize;
   draw_sprite_part_ext(sprite6, 0, sx, sy, cellSize,cellSize, mousex,mousey, scale,  scale, c_white, 0.5
           );
}

I am not really sure how to finish the system though. I already have it so I can drag the talent icons around but how to I make it so I can drop them in an equipment slot and how do I make it so each slot has a different button associated with it?
here are the sprites I have made and am working with. the equipment slots would be the 9 on the bottom of the one on the right hand side. if it would work better to have a separate sprite for the equipment slots I could make new sprites