Develop a Mac Application

I have a Windows 10 program that I need to be developed for macOS from version 10.6 onwards. This program randomly displays some characters in the screen by performing the following tasks: 1) The program has a dialog-box interface to request the user input. This dialog-box has to be modeless and minimizable in the application’s status bar. 2) The input data are: a) Size of the window (a square) in which to display the characters; b) Background/foreground color of the window above; c) Location in which to display the window, to be chosen between the 4 corners of the screen (whatever the resolution is). d) Font and font size of the character to be displayed in the window above. e) A check-box asking if the user wants a beep to be played when showing each character. f) Time range for the displaying of the characters in minutes, e.g. from 2 min. to 20 min. g) Time in seconds while each character has to remain on screen. 3) The are 3 commands (buttons) in the dialog-box: a) Start: when pressed the program: - displays the word “Running” in the dialog-box; - displays a random character (A-Z/0-9) in the window described in point 2/a/b/c/d at the random interval of time defined by the range of point 2/f and for the duration specified in point 2/g; - when displayed a character a beep has to be played if requested in 2/e. - the characters start to be displayed according with the random interval and the duration requested in 2/f and 2/g; - the window displaying the character must stay on top of the currently running applications (top of Z-order) but without acquiring the input focus which has to remain to the current application; - each character displayed has to be written (added) to a string to be saved in the text file (see 4/c). b) Pause: when pressed the word “Pause” has to be displayed in the dialog-box and the program suspends to display characters until the user press “Start” again. c) End: when pressed the program opens the File-Save-Dialog for saving the text file in which to store the string of characters displayed. ------ For anything not described here above the program must replicate exactly the same behavior of the Windows version which I will provide to the developer. The delivering of the source code is required. The delivery date required is in 2 weeks form the agreement.