simply_gui.py

# pip install ttkbootstrap
import ttkbootstrap as ttk 

FONT = ('calibri', 18)

class App(ttk.Window) :
    def __init__(self) :
        super().__init__(themename='darkly')
        self.title('app')
        self.geometry('600x300')
        self.resizable(0,0)
        self.bind('<Escape>', func=lambda *k: self.quit())
        self.bind('<Control-l>', func=lambda *k: entry.focus())

        # var
        self.entry_var = ttk.StringVar()
        self.entry_var.trace('w', callback=self.input_to_output)
        self.checkbox1_var = ttk.BooleanVar(value=True)
        self.checkbox1_var.trace('w', callback=self.input_to_output)
        self.checkbox2_var = ttk.BooleanVar()
        self.checkbox2_var.trace('w', callback=self.input_to_output)
        self.font_size_var = ttk.IntVar(value=FONT[1])
        self.font_size_var.trace('w', callback=self.update_font_size)
        self.font_size_var_str = ttk.StringVar()

        self.mainframe = ttk.Frame(self)
        self.mainframe.pack(expand=True, fill='both', padx=40, pady=20)
        # ttk.Label(self.mainframe, background='red').pack(expand=True, fill='both')
        # grid
        self.mainframe.columnconfigure((0,1,2,3,4), weight=1, uniform='a')
        self.mainframe.rowconfigure((0,1,2,3), weight=1, uniform='a')

        # layouts
        self.input_box()
        self.output_box()
        self.bottom_box()

        # call
        self.update_font_size()
        
        # keep app running
        self.mainloop()

    def input_to_output(self, *k) :
        text = self.entry_var.get()
        #clear
        output1.delete('1.0', ttk.END)
        output2.delete('1.0', ttk.END)
        btn1['state'] = 'disable'
        btn2['state'] = 'disable'
        
        if self.checkbox1_var.get() :
            output1.insert('1.0', text)
            if text != '' :
                btn1['state'] = 'enable'
        if self.checkbox2_var.get() :
            output2.insert('1.0', text)
            if text != '' :
                btn2['state'] = 'enable'

    def update_font_size(self, *k) :
        current_font_size = self.font_size_var.get()
        current_font_size_str = f'{current_font_size}pt'
        self.font_size_var_str.set(value=current_font_size_str)

        FONT_ = (FONT[0], current_font_size)
        entry['font'] = FONT_
        output1['font'] = FONT_
        output2['font'] = FONT_

    def copy_text(self, text) :
        text = text.get('1.0', ttk.END)
        self.clipboard_clear()
        self.clipboard_append(text)
        
    def input_box(self) :
        global entry
        entry = ttk.Entry(self.mainframe, font=FONT, textvariable=self.entry_var)
        entry.grid(row=0, column=0, columnspan=5, sticky='nsew')

    def output_box(self) :
        global output1, output2, btn1, btn2
        output1 = ttk.Text(self.mainframe, font=FONT)
        output2 = ttk.Text(self.mainframe, font=FONT) 
        output1.grid(row=1, column=0, columnspan=4, sticky='nsew')
        output2.grid(row=2, column=0, columnspan=4, sticky='nsew')

        btn1 = ttk.Button(self.mainframe, text='copy', width=50, bootstyle='warning', state='disable', command=lambda: self.copy_text(output1))
        btn2 = ttk.Button(self.mainframe, text='copy', width=50, bootstyle='warning', state='disable', command=lambda: self.copy_text(output2))
        btn1.grid(row=1, column=4, sticky='nsew')        
        btn2.grid(row=2, column=4, sticky='nsew')

    def bottom_box(self) :
        slider = ttk.Scale(self.mainframe,  bootstyle='warning', variable=self.font_size_var, from_=16, to=24)
        label = ttk.Label(self.mainframe, textvariable=self.font_size_var_str)
        checkbox1 = ttk.Checkbutton(self.mainframe, text='option1', bootstyle='danger-toggle-square', variable=self.checkbox1_var)
        checkbox2 = ttk.Checkbutton(self.mainframe, text='option2', bootstyle='danger-toggle-square', variable=self.checkbox2_var)
        slider.grid(row=3, column=0, columnspan=2, sticky='nsew')
        label.grid(row=3, column=2, sticky='nsew', padx=15)
        checkbox1.grid(row=3, column=3, sticky='nsew')
        checkbox2.grid(row=3, column=4, sticky='nsew')

# call and running the app
App()