TFT LCD touch screen mapping by external keypad

Dear every body,

I'm doing project about lcd tft 7inch 800x480 and stm32f746.

Currently, i want use external keypad (or external button), not use touch screen pannel.

Example: 

http://hshop.vn/products/ban-phim-ma-tran-mem-4x4

I have 1 button on LCD:

// { BUTTON_CreateIndirect, 'Browse', ID_BUTTON_0, 13, 8, 100, 20, 0, 0x0, 0 },

(x,y) =  (13,8).

width = 100.

height = 20.

=> (x,y) center = (13+100/2 = 63,8+20/2=18).

When 1 keypad or button pressed, i checked that ok.

How to mapping 1 key pressed to WM_NOTIFICATION_CLICKED event of 

ID_BUTTON_0 (ID_BUTTON_0 is displayed on LCD)? After that, emwin will do something: show dialog...

Can you tell me solutions, please?

Thank you so much!