How to get FlowLayoutPanel.AutoSize to work with FlowBreak

Question

I have a problem with a FlowLayoutPanel and I don't know how to solve it.

I'm placing two FlowLayoutPanels inside another; the second inner flp has 3 buttons inside.

The properties from FlowLayoutPanel child are:

FlowDirection = LeftToRight;
AutoSize = true;
AutoSizeMode = GrowAndShrink;
WrapContents = true;

Now I set for each button the FlowBreak property to true, however the behavior I see is not the one I want, I want the FlowLayoutPanel to shrink to the width of the buttons,

Changing FlowDirection to UpToDown is not an option.

Anyone know why the AutoSize is not working?

this is the code.

//
//FlowLayoutPanel1
//
this.FlowLayoutPanel1.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
this.FlowLayoutPanel1.Controls.Add(this.FlowLayoutPanel3);
this.FlowLayoutPanel1.Location = new System.Drawing.Point(84, 77);
this.FlowLayoutPanel1.MinimumSize = new System.Drawing.Size(10, 10);
this.FlowLayoutPanel1.Name = "FlowLayoutPanel1";
this.FlowLayoutPanel1.Size = new System.Drawing.Size(308, 265);
this.FlowLayoutPanel1.TabIndex = 0;
//
//FlowLayoutPanel3
//
this.FlowLayoutPanel3.AutoSize = true;
this.FlowLayoutPanel3.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
this.FlowLayoutPanel3.Controls.Add(this.Button1);
this.FlowLayoutPanel3.Controls.Add(this.Button2);
this.FlowLayoutPanel3.Controls.Add(this.Button3);
this.FlowLayoutPanel3.Location = new System.Drawing.Point(127, 3);
this.FlowLayoutPanel3.MinimumSize = new System.Drawing.Size(10, 10);
this.FlowLayoutPanel3.Name = "FlowLayoutPanel3";
this.FlowLayoutPanel3.Size = new System.Drawing.Size(162, 87);
this.FlowLayoutPanel3.TabIndex = 1;
//
//Button1
//
this.FlowLayoutPanel3.SetFlowBreak(this.Button1, true);
this.Button1.Location = new System.Drawing.Point(3, 3);
this.Button1.Name = "Button1";
this.Button1.Size = new System.Drawing.Size(75, 23);
this.Button1.TabIndex = 0;
this.Button1.Text = "Button1";
this.Button1.UseVisualStyleBackColor = true;
//
//Button2
//
this.FlowLayoutPanel3.SetFlowBreak(this.Button2, true);
this.Button2.Location = new System.Drawing.Point(3, 32);
this.Button2.Name = "Button2";
this.Button2.Size = new System.Drawing.Size(75, 23);
this.Button2.TabIndex = 1;
this.Button2.Text = "Button2";
this.Button2.UseVisualStyleBackColor = true;
//
//Button3
//
this.Button3.Location = new System.Drawing.Point(3, 61);
this.Button3.Name = "Button3";
this.Button3.Size = new System.Drawing.Size(75, 23);
this.Button3.TabIndex = 2;
this.Button3.Text = "Button3";
this.Button3.UseVisualStyleBackColor = true;

Answer 1

It is a bug, it's been around for a very long time. The issue is that the layout engine for FlowLayoutPanel calculates the width of the first row wrong, including the width of the 2nd control, even though it got wrapped to the second row.

The workaround is silly but effective, add a dummy Panel with a Width of 0 after the 1st control. If you are doing this with the designer then drop it first and drag it in the right place, to the right of the 1st control. Then set its Margin to (0, 0, 0, 0) and Size to (0, 0) in the Properties window.