LibreOffice Draw: drawing 90 degree curve line (1/4 circle)

I have a long vertical text box surrounded with borders and rounded corners. I’d like to have 3 text boxes with borders in the shape of a plus sign (long vertical text box with a horizontal text box on each side). I’d like the to have the vertical line of the center text box broken with 90 degree curves so the overall border will surround the three text boxes.

I’d like to draw a curved line 90 degrees so I can duplicate them, rotate them, surround the text boxes and connect straight lines to these curved lines.

My problem is that I can not figure out how to draw a simple 1/4 circle curved line in LibreOffice Draw.

See answer in /question/225610/.

But maybe, you can begin with a Cross¹ shape, add four Circles, Merge them, and use the result to Subtract from a Square. Choose menu Shape - Insert - Basic Shapes to insert Cross, Circle, Square. Choose menu Shape to Merge and Subtract.

image description

¹ Note the control point (a small circle) with which you can change the shape of the Cross. Smaller notches and circles will leave less dull corners.

Tested with LibreOffice (x86); OS: Windows 6.1.

Add Answer is reserved for solutions. If you think the answer is not satisfactory, add a comment below, or click edit (below your question) to add more information. Thanks.

Check the mark (Answer markCorrect answer mark) to the left of the answer that solves your question.

If the answer helped you, you can mark the up arrow (Upvote mark) that is on the left (to vote, you need to have karma of at least 5).