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Editorial Team
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Asked: 2026-06-11T01:51:51+00:00

Is there a reason why a .NET WinForms TabPage doesn’t fully repaint its background

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Is there a reason why a .NET WinForms TabPage doesn’t fully repaint its background when I resize the Form? It should be completely white (in Windows 7), but a portion remains gray (SystemColors.Control, most likely). Whenever I hit the maximize button, currently visible TabPage background doesn’t get redrawn. Also, if I resize it, I need to move the form past the screen boundaries in order for it to get painted.

The same thing happens if I minimize and then restore the form. In that case the TabPage background remains grey. Child controls are rendered properly (labels, for example, keep their white backgrounds).

I am using Windows 7 32-bit, .NET 3.5. Tab control was added using the Visual Studio designer, and contains a couple of labels and two text boxes. I haven’t changed any native style flags related to paint messages.

[Edit]

I have created a test project, source is uploaded here.

This is how the window looks initially:

Form initial state

This is how the window looks after I minimize it and then restore it:

Minimized, then restored

Note the change in TabPage background color.

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1 Answer

  1. Editorial Team

    Ok, I recon your problem can be solved by doing the folowing steps:

    For the tabPage set UseVisualStyleBackColor to False and just set its BackColor to the color you want, in this case White

    Also instead of setting anchor to all sides, just set Dock to Fill.
    Generally avoid setting size for labels, try only anchors for them.

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