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Fix managed TitleBar affecting Control placement #117

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Fix managed TitleBar affecting Control placement #117

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2d39fda
Initial plan
Copilot Apr 3, 2026
a4f84e8
Fix managed TitleBar affecting control placement: offset DisplayRecta…
Copilot Apr 3, 2026
e59d8fb
Fix non-docked controls also offset by title bar height
Copilot Apr 3, 2026
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42 changes: 42 additions & 0 deletions src/Modern.Forms/ControlAdapter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,50 @@ public override Rectangle ClientRectangle {
}
}

// The DisplayRectangle accounts for the managed title bar so that
// child controls are laid out below it, similar to system decorations.
public override Rectangle DisplayRectangle {
get {
var rect = base.DisplayRectangle;
var titleBarOffset = TitleBarOffset;

if (titleBarOffset > 0) {
rect.Y += titleBarOffset;
rect.Height -= titleBarOffset;
}

return rect;
}
}

public WindowBase ParentForm { get; }

protected override void OnLayout (LayoutEventArgs e)
{
base.OnLayout (e);

// After the normal layout has run, manually position the title bar at
// the top and offset all other controls below it. The title bar acts as
// non-client chrome and should not participate in the normal layout flow.
if (ParentForm is Form form && form.TitleBar.Visible) {
var offset = form.TitleBar.Height;

form.TitleBar.SetBounds (0, 0, Width, offset);

// Offset all non-titlebar controls so they appear below the title bar,
// matching the behavior of system decorations where the title bar is
// not part of the client area.
foreach (var control in Controls.GetAllControls ()) {
if (control != form.TitleBar)
control.Top += offset;
}
}
}

// Returns the height of the visible managed title bar, or 0.
private int TitleBarOffset =>
ParentForm is Form form && form.TitleBar.Visible ? form.TitleBar.Height : 0;

protected override void OnPaint (PaintEventArgs e)
{
// We have this special version for the Adapter because it is
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