Remove control from Form: space is still occupied - winforms

Question

I have a Form and want to toggle show and hide the RichTextBox.
If I hide the control, the control should give up the space reservation, but actually it doesn't.
it is Removed, but the original space reserved by rtbcontrol is still visible as empty grey space.
It seems, it affects only the Controls, which are anchored to the bottom.
I made a small sample for demonstrating my problem:
Desinger:
namespace HideShowTest
{
partial class Form1
{
/// <summary>
/// Erforderliche Designervariable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Verwendete Ressourcen bereinigen.
/// </summary>
/// <param name="disposing">True, wenn verwaltete Ressourcen gelöscht werden sollen; andernfalls False.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Vom Windows Form-Designer generierter Code
/// <summary>
/// Erforderliche Methode für die Designerunterstützung.
/// Der Inhalt der Methode darf nicht mit dem Code-Editor geändert werden.
/// </summary>
private void InitializeComponent()
{
this.richTextBox1 = new System.Windows.Forms.RichTextBox();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.button3 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// richTextBox1
//
this.richTextBox1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.richTextBox1.Location = new System.Drawing.Point(13, 126);
this.richTextBox1.Name = "richTextBox1";
this.richTextBox1.Size = new System.Drawing.Size(289, 80);
this.richTextBox1.TabIndex = 0;
this.richTextBox1.Text = "";
//
// button1
//
this.button1.Location = new System.Drawing.Point(13, 13);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(92, 23);
this.button1.TabIndex = 3;
this.button1.Text = "top anchor";
this.button1.UseVisualStyleBackColor = true;
//
// button2
//
this.button2.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)));
this.button2.Location = new System.Drawing.Point(13, 75);
this.button2.Name = "button2";
this.button2.Size = new System.Drawing.Size(92, 23);
this.button2.TabIndex = 2;
this.button2.Text = "bottom anchor";
this.button2.UseVisualStyleBackColor = true;
//
// button3
//
this.button3.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));
this.button3.Location = new System.Drawing.Point(227, 75);
this.button3.Name = "button3";
this.button3.Size = new System.Drawing.Size(75, 23);
this.button3.TabIndex = 1;
this.button3.Text = "Hide Rtb";
this.button3.UseVisualStyleBackColor = true;
this.button3.Click += new System.EventHandler(this.button3_Click);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(314, 226);
this.Controls.Add(this.button1);
this.Controls.Add(this.button2);
this.Controls.Add(this.button3);
this.Controls.Add(this.richTextBox1);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.RichTextBox richTextBox1;
private System.Windows.Forms.Button button3;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button1;
}
}
and Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace HideShowTest
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button3_Click(object sender, EventArgs e)
{
if (richTextBox1.Visible)
{
richTextBox1.Hide();
this.Height -= richTextBox1.Height;
}
else
{
richTextBox1.Show();
this.Height += richTextBox1.Height;
}
button3.Text = richTextBox1.Visible ? "Hide Rtb" : "Show Rtb";
}
}
}
If I click "Hide Rtb", the bottom anchor button wanders up (it should stay at the same place).

Answer 1

Edit: since you edited the question and asked about a totally different thing:
You have the Anchor property of button2 set to Left and Bottom, so it's clearly going to move when you resize the form in order to maintain the same distance between the button and the bottom of the form.
To avoid that, you can either set the Anchor property to Top or change the location of the button accordingly when changing the size of the form. For example:
int t = button2.Top;
ToggleRtbVisibility();
button2.Top = t;
Original answer:
1) If you want to toggle "show and hide", do hide and show the control, do not remove it.
2) I suspect that you checked the Size property of the form instead of the ClientSize property, but you're changing the value of the ClientSize. Also, don't use fixed numbers for changing the size, calculate them instead.
Try something like this:
private void ToggleRtbVisibility(bool hide)
{
rtbLog.Visible = !hide;
int preservedHeight = rtbLog.Height + rtbLog.Margin.Top + rtbLog.Margin.Bottom;
if (hide)
{
this.Height -= preservedHeight;
}
else
{
this.Height += preservedHeight;
}
}
And if you don't want use a parameter to explicitly specify whether to show or hide the control, you can change the above method to something like:
private void ToggleRtbVisibility()
{
rtbLog.Visible = !rtbLog.Visible;
int preservedHeight = rtbLog.Height + rtbLog.Margin.Top + rtbLog.Margin.Bottom;
if (rtbLog.Visible == false)
this.Height -= preservedHeight;
else
this.Height += preservedHeight;
}
Hope that helps.