Try it. It is designed to map MessageBox. However, he does not change his style based on the OS. This is similar to Vista.
Here is an example of this in action, from it the original house (Paint.NET plugin). It will expand to match the prompt.

InputBox.cs:
internal partial class InputBoxForm : Form
{
Size lbltextoriginalsize;
Size pnlwhiteoroginalsize;
public InputBoxForm(string text, string defaultvalue, string caption)
{
InitializeComponent();
this.pnlWhite.Resize += new System.EventHandler(this.pnlWhite_Resize);
this.lblText.Resize += new System.EventHandler(this.lblText_Resize);
picIcon.Image = SystemIcons.Question.ToBitmap();
lbltextoriginalsize = lblText.Size;
pnlwhiteoroginalsize = pnlWhite.Size;
this.lblText.Text = text;
this.txtOut.Text = defaultvalue;
this.Text = caption;
}
private void lblText_Resize(object sender, EventArgs e)
{
pnlWhite.Size += lblText.Size - lbltextoriginalsize;
}
private void pnlWhite_Resize(object sender, EventArgs e)
{
this.Size += pnlWhite.Size - pnlwhiteoroginalsize;
}
public string Value
{
get { return txtOut.Text; }
}
}
public static class InputBox
{
public static DialogResult Show(string text, out string result)
{
return ShowCore(null, text, null, null, out result);
}
public static DialogResult Show(IWin32Window owner, string text, out string result)
{
return ShowCore(owner, text, null, null, out result);
}
public static DialogResult Show(string text, string defaultValue, out string result)
{
return ShowCore(null, text, defaultValue, null, out result);
}
public static DialogResult Show(IWin32Window owner, string text, string defaultValue, out string result)
{
return ShowCore(owner, text, defaultValue, null, out result);
}
public static DialogResult Show(string text, string defaultValue, string caption, out string result)
{
return ShowCore(null, text, defaultValue, caption, out result);
}
public static DialogResult Show(IWin32Window owner, string text, string defaultValue, string caption, out string result)
{
return ShowCore(owner, text, defaultValue, caption, out result);
}
private static DialogResult ShowCore(IWin32Window owner, string text, string defaultValue, string caption, out string result)
{
InputBoxForm box = new InputBoxForm(text, defaultValue, caption);
DialogResult retval = box.ShowDialog(owner);
result = box.Value;
return retval;
}
}
InputBox.Designer.cs:
partial class InputBoxForm
{
private System.ComponentModel.IContainer components = null;
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.pnlWhite = new System.Windows.Forms.Panel();
this.lblText = new System.Windows.Forms.Label();
this.picIcon = new System.Windows.Forms.PictureBox();
this.txtOut = new System.Windows.Forms.TextBox();
this.btnOK = new System.Windows.Forms.Button();
this.btnCancel = new System.Windows.Forms.Button();
this.pnlWhite.SuspendLayout();
((System.ComponentModel.ISupportInitialize)(this.picIcon)).BeginInit();
this.SuspendLayout();
this.pnlWhite.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.pnlWhite.BackColor = System.Drawing.Color.White;
this.pnlWhite.Controls.Add(this.lblText);
this.pnlWhite.Controls.Add(this.picIcon);
this.pnlWhite.Controls.Add(this.txtOut);
this.pnlWhite.Location = new System.Drawing.Point(0, 0);
this.pnlWhite.Margin = new System.Windows.Forms.Padding(0);
this.pnlWhite.MinimumSize = new System.Drawing.Size(235, 84);
this.pnlWhite.Name = "pnlWhite";
this.pnlWhite.Size = new System.Drawing.Size(235, 84);
this.pnlWhite.TabIndex = 0;
this.lblText.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Left)));
this.lblText.AutoSize = true;
this.lblText.Location = new System.Drawing.Point(64, 26);
this.lblText.Margin = new System.Windows.Forms.Padding(3, 0, 30, 30);
this.lblText.MinimumSize = new System.Drawing.Size(159, 0);
this.lblText.Name = "lblText";
this.lblText.Size = new System.Drawing.Size(159, 13);
this.lblText.TabIndex = 2;
this.picIcon.BackColor = System.Drawing.Color.White;
this.picIcon.Location = new System.Drawing.Point(25, 26);
this.picIcon.Name = "picIcon";
this.picIcon.Size = new System.Drawing.Size(32, 32);
this.picIcon.TabIndex = 1;
this.picIcon.TabStop = false;
this.txtOut.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.txtOut.Location = new System.Drawing.Point(67, 50);
this.txtOut.Name = "txtOut";
this.txtOut.Size = new System.Drawing.Size(159, 20);
this.txtOut.TabIndex = 5;
this.btnOK.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
this.btnOK.DialogResult = System.Windows.Forms.DialogResult.OK;
this.btnOK.Location = new System.Drawing.Point(42, 96);
this.btnOK.Name = "btnOK";
this.btnOK.Size = new System.Drawing.Size(88, 26);
this.btnOK.TabIndex = 3;
this.btnOK.Text = "OK";
this.btnOK.UseVisualStyleBackColor = true;
this.btnCancel.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
this.btnCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel;
this.btnCancel.Location = new System.Drawing.Point(138, 96);
this.btnCancel.Name = "btnCancel";
this.btnCancel.Size = new System.Drawing.Size(88, 26);
this.btnCancel.TabIndex = 4;
this.btnCancel.Text = "Cancel";
this.btnCancel.UseVisualStyleBackColor = true;
this.AcceptButton = this.btnOK;
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.CancelButton = this.btnCancel;
this.ClientSize = new System.Drawing.Size(235, 133);
this.Controls.Add(this.btnCancel);
this.Controls.Add(this.btnOK);
this.Controls.Add(this.pnlWhite);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Name = "InputBoxForm";
this.ShowIcon = false;
this.ShowInTaskbar = false;
this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
this.pnlWhite.ResumeLayout(false);
this.pnlWhite.PerformLayout();
((System.ComponentModel.ISupportInitialize)(this.picIcon)).EndInit();
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.Panel pnlWhite;
private System.Windows.Forms.PictureBox picIcon;
private System.Windows.Forms.Label lblText;
private System.Windows.Forms.Button btnOK;
private System.Windows.Forms.Button btnCancel;
private System.Windows.Forms.TextBox txtOut;
}