RichTextBox is a control which provides formatting features that TextBox control does not provide. 
For instance, you can customize the text’s color, style and/or size. So, you can apply formatting to a word, 
a line or all of the paragraph. RichTextBox is useful if you want to have more control over styling, 
but although it supports search in its content by the “Find” functionality, it does not have a search UI, 
so this reduces control’s user-friendly design. If you need to search something in RichTextBox you should add new code blocks, functions, UI controls.

In this project, we derived a searchable RichTextBox control from RichTextBox which provides search(Find) functionality with a “Find” pop-up. 
Searchable RichTextBox does not assist any UI customization nevertheless it allows using ‘Control + F’ function in the text content.