drawing a grid over an array position?

How do I add a selection box around the currently selected tile in my map editor.

An example would be selecting the first tile in the top row. When my mouse is over the position how would I add a selection box around the tile. I kindof want the selection box to move tile by tile.

heres a quick bit of code that draws my tiles to screen. If somebody can give me a hint or an example of how to do the above I would appreciate it.

Function factory()
	Local x:Int,y:Int
	Local mapX:Int,mapY:Int
	Local map[36,22]
	Local mX:Int,mY:Int

	mapX = 40
	mapY = 40
	
	
		For x = 0 To 35
			For y = 0 To 21
				map[x,y] = 1
			Next
		Next
		
	
		Repeat
			mX = MouseX()
			my = MouseY()                            			
			Cls	

				
				For x = 1 To 35
					For y = 1 To 21
 						
						If map[x,y] = 1
							DrawImage rplat,mapX+(x*20),mapY+(y*20),1
						EndIf
					Next
				Next
							
			Flip
			
		Until KeyHit(KEY_ESCAPE)
End Function

The way I always do that is to just check when rendering, then blit it using the coords the image(Tile) would be drawn to.


I.eudeo

for
for
DrawTile
if MapX = SelectedX and MapY = SelectedY then RectAroundTile
next
next