Block clicks with mouse on the form

Hello

I am trying to prevent that the user can click to the form.
I tried the ShowDialog over the form and it works however the form doesn't show the cursor icon when hover to the form which is "No". (I did setup the cursor icon in the form properties).

 

So in short this is happening:

Two forms are there. One form which is maximized and second form which is over on the first form. Both form are setup as "Topmost". The main problem is that if I click to the first form which is maximized then the second form will be behind of the first form. I want prevent that the user could click to the first form so the second form will staying there visible. Meanwhile the first form would show the cursor icon "no". 

 

How can I prevent that the people could click to the form? 

 

Thank you in advance the answers.