SettingsForm.cs

using System;
using System.Windows.Forms;

namespace WorkTimer
{
    public partial class SettingsForm : Form
    {
        public AppSettings Settings { get; private set; }

        public SettingsForm(AppSettings currentSettings)
        {
            InitializeComponent();
            Settings = currentSettings;

            txtIdleTime.Text = (Settings.IdleSecondsForPause / 60).ToString();
            txtAutoResume.Text = (Settings.ManualPauseSecondsForAutoResume).ToString();
            txtWpm.Text = Settings.WpmForFullMeter.ToString();
            chkAlwaysOnTop.Checked = Settings.AlwaysOnTop;
            trackBarOpacity.Value = (int)(Settings.Opacity * 100);
            lblOpacity.Text = $"{trackBarOpacity.Value}%";
        }

        private void btnOk_Click(object sender, EventArgs e)
        {
            if (ValidateInputs())
            {
                Settings.IdleSecondsForPause = int.Parse(txtIdleTime.Text) * 60;
                Settings.ManualPauseSecondsForAutoResume = int.Parse(txtAutoResume.Text);
                Settings.WpmForFullMeter = int.Parse(txtWpm.Text);
                Settings.AlwaysOnTop = chkAlwaysOnTop.Checked;
                Settings.Opacity = trackBarOpacity.Value / 100.0;

                this.DialogResult = DialogResult.OK;
                this.Close();
            }
        }

        private bool ValidateInputs()
        {
            bool valid = true;
            valid &= int.TryParse(txtIdleTime.Text, out int idle) && idle >= 1;
            valid &= int.TryParse(txtAutoResume.Text, out int resume) && resume >= 1;
            valid &= int.TryParse(txtWpm.Text, out int wpm) && wpm >= 10;

            if (!valid)
            {
                MessageBox.Show("Please enter valid positive numbers for all fields.", "Invalid Input", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            return valid;
        }

        private void trackBarOpacity_Scroll(object sender, EventArgs e)
        {
            lblOpacity.Text = $"{trackBarOpacity.Value}%";
        }
    }
}