[Enhancement] PySimpleGUI-TK Ability to force window focus

When running multiple windows, serially where one is closed before another open, on Windows,
new windows do not receive focus after the first window. Only the initial window is given focus after creation.

Where is a workaround available. Use this when you create your window:

   window.TKroot.focus_force()         # Force this window to have focus

   window.Element('-FIRST-INPUT-FIELD-KEY').SetFocus()   # Force this Element to have focus

This will focus the window and move the cursor to the indicated Element.

Inizia riproducendo il comportamento di Windows con finestre PySimpleGUI-TK create in sequenza, quindi leggi i punti di ingresso del focus esistenti indicati nell’issue: window.TKroot.focus_force() e Element('-FIRST-INPUT-FIELD-KEY').SetFocus(). Il lavoro è completato quando le finestre appena create ricevono il focus in modo coerente senza richiedere questo workaround, mentre l’elemento indicato può ancora ricevere il focus del cursore.