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POTabControl flickering when changing the tab's icon
 

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  1. POTabControl flickering when changing the tab's icon
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    <p>About to lose my mind here. I've been googling for an hour trying to solve this minor, but incredibly aggravating problem.</p> <p>I have a <code>TabControl</code> on my form with two tabs. Each of those tabs has a 16x16 icon and some text. Nothing crazy going on here.</p> <p>I need to make one of the tab icons blink under certain circumstances. So I created two images, <img src="https://i.stack.imgur.com/q1E2Y.png" alt="light_on.png"> and <img src="https://i.stack.imgur.com/G8oNf.png" alt="light_off.png"> and added them to the <code>ImageList</code> used by the <code>TabControl</code>. I set up a background timer that toggles between the two images to simulate a blinking icon. Works fine. </p> <p>However, it's causing all of the tab headers to redraw, which is making them flicker. </p> <p>The <code>TabControl</code> does not support double-buffering, no matter what you try to do.</p> <p>I've found people have some success taming flickering using this code:</p> <pre><code> Protected Overrides ReadOnly Property CreateParams() As CreateParams Get Dim cp As CreateParams = MyBase.CreateParams cp.ExStyle = cp.ExStyle Or &amp;H2000000 Return cp End Get End Property </code></pre> <p>That works, as in, it doesn't flicker... but the icons also don't visually change anymore unless the mouse cursor hovers over something that causes a redraw. </p> <p>Does anyone have any alternate solutions or tricks that might work? This is actually a pretty essential feature to the software.</p> <p>Skeleton code:</p> <pre><code>Public Class Form1 Dim BlinkTimer As Windows.Forms.Timer Dim BlinkToggler As Boolean = False Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load InitBlinker() End Sub Private Sub InitBlinker() BlinkTimer = New Windows.Forms.Timer AddHandler BlinkTimer.Tick, AddressOf Blinker_Tick With BlinkTimer .Enabled = True .Interval = 250 End With StartBlinker() End Sub Public Sub StartBlinker() SomeTabPage.ImageKey = "light_off.png" BlinkToggler = False BlinkTimer.Start() End Sub Public Sub StopBlinker() SomeTabPage.ImageKey = "light_off.png" BlinkToggler = False BlinkTimer.Stop() End Sub Private Sub Blinker_Tick() If BlinkToggler Then SomeTabPage.ImageKey = "light_on.png" Else SomeTabPage.ImageKey = "light_off.png" End If BlinkToggler = Not BlinkToggler End Sub End Class </code></pre>
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    1. USuser1003916
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    1. CO... I could be WAAY off here, but what about an animated gif and then you don't have to worry about it?
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      1. USJohn Bustos
    2. COThe TabControl can't be double-buffered, so you probably have to live with this limitation or design your flashing light bulbs to flash somewhere else on the screen.
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      1. USLarsTech
    3. CO@JohnBustos I tried an animated gif, doesn't work (doesn't animate). That's the kind of suggestion I was looking for, thanks.
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