This is the expected behavior. Based on the documentation, the 3rd return argument from this function can be a "vector of integers indicating which mouse buttons you pressed (1 for left, 2 for middle, 3 for right)".
When double-clicking quickly using the middle button the Figure's SelectionType property becomes "Open" based on the
. This can be verified by the following:
f = gcf;
f.SelectionType %should return 'normal'
[x,y,button] = ginput(3) %click right button rapidly on axes
f.SelectionType %should now be 'open'
This is considered to be a "Left click" in ginput. When clicks are made rapidly several times, ginput will register all those clicks and since all clicks after the first are "Open", they all translate to button "1" or left click.
