custom splittable textbox(by shape) using c#-.Net

Question

hello!

 

i like using a textbox in c# that can be split a part of text inside textbox was fullcontrol and other parts of the object(same textbox) was readonly as following :

 

 

gray background color parts is disable for editing or readonly=true .

white background color part is enable for editing or readonly=false.

black foreground color text for pretyped and pink foreground color text for typing now(input user)

and dash  splitters was for do split a different parts of textbox texets.but all parts are just a textbox(no more no array)

 Notice: gray parts typed last time and disable for editing .but white part is enable for changing and editing.

please do help me for creation like this textbox

....