title: How to get ROI bounding box coordinates with mouse clicks instead of guess & check
body: <p>So I am attempting to take a screenshot of my monitor and only grab part of the screen when doing so. I know I can use mss or opencv, pillow or any other screenshotting library that supports bounding boxes... However, instead of randomly guessing on what the coordinate are... and what I mean by this is taking a screenshot with bounding box coordinates set, and seeing if it is anywhere close to what I am actually trying to get the picture of.</p>
  
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  <p>For example: my trial coordinates would be 10,10,500,500 when in reality my actual coordinates that I need are 15,40,200,300 (these coordinates are made up)</p>
  
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  <p>My idea to solve this problem is to either have a tool that allows me to click and drag a bounding box around the image (part of the screen) that I need and have the program return the results, such as 15,40,200,300. Also, if I box could be drawn as it is shown that would be really helpful!
  If there is another way of doing achieving this goal I would be open to this as well.</p>
  
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  <p>Thank you.</p>