How to create multiple buttons like this?

JamesDo

I want to make a operation span task. I need to present multiple buttons with labels being different letters. Users will click on these buttons and the letters will appear as shown in the figure below:

I have experiences with application programming and I can make this easily using Java, C, .Net languages. However, I am new to Opensesame so I don't know what I can do with Opensesame to make what I described above. Can I make this directly with Opensesame GUI? Can I create multiple buttons in some window in Opensesame? Or do I need to manually draw everything in a sketchpad and listen events from mouse to create other effect like button click and so on?

I don't mean to ask you for a detailed way to make what I want. I just want to have some insight on which direction I need to go, which part on Opensesame manual I need to read. For example, I found that there is a page about Canvas in Opensesame. Do I need to read about Canvas?

Thank you very much.

JamesDo

I found the answer for my question after watch this tutorial video:
https://youtube.com/watch?v=K2dcG_7Hs3Y&t=177s

I can draw filled rectangle shapes and texts (which are single letters in this case) in a sketchpad. After that, I use a mouse response object to collect the mouse click data.

One thing I noted is that Opensesame run very slow when there are many text items in the sketchpads. So instead of drawing a square shape and a letter for every button, I draw an image of that letter button and the response time is much shorter.