let sobreWindow = null;
ipcMain.on('abrir-janela-sobre', () => {
    console.log(sobreWindow);
    if(sobreWindow == null){
        let sobreWindow = new BrowserWindow({
            width: 300,
            height:200
        });
        sobreWindow.on('closed', () => {
            sobreWindow = null;
        });
    }
    sobreWindow.loadURL('file://'+__dirname+'/app/sobre.html');
}); 
            