I'm using the style "Charcoal Dark Slate" right out of the box and having issues with the TCategoryPanelGroup not refreshing its category panels.

In this setup all category panels all expanded. Each panel has ONE control, a TFrame with a few child controls. The TFrame has its Align property set to alClient.

If I collapse the middle one, every following panel isn't redrawing all controls. I have to move the mouse over them to get them redrawn. If I collapse the first panel, panel 2 and 3 aren't redrawn etc... (basically all panels that moved up)

I have tried to Invalidate(), Repaint() and Refresh() the TCategoryPanelGroup on the collapse event OnCollapse. I have also tried to Invalidate(), Repaint() and Refresh() the panel itself in desperation. Nothing helps.

I noticed that all panels are repainted on resize. My workaround now is to have the OnCollapse and OnExpand event handlers to quickly resize the TCategoryPanelGroup control.

void __fastcall TGraph_Form::CategoryPanelCollapse(TObject *Sender) {

    TCategoryPanel      *p = reinterpret_cast<TCategoryPanel*>(Sender);
    TCategoryPanelGroup *g = reinterpret_cast<TCategoryPanelGroup*>(p->PanelGroup);

    // Fix style bug on collapse events
    // Force a resize to redraw all panels
    g->Width++;
    g->Width--;
}

Adjusting the Height property of the TCategoryPanelGroup will not force all panels to redraw, it has to be the Width property.

Have I missed something here or is this indeed another VCL style bug?