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Original Reporter info from Mantis: OldRuby

• Reporter name: Colin Liebenrood

Description:

TPageControl.IndexofTabAt returning wrong values when some tabs are hidden.

Example: 16 tabs (0..15) with tabs 4..9 and 12 hidden. Mouse over tab 10 (5th visible) returns 11, should be 10.

The cause is in function TabIndexAtClientPos in file C:\lazarus\lcl\include\customnotebook.inc, where
the return vaule is calculated. The following rewrite of this function returns the correct value.

TCustomTabControl.TabIndexAtClientPos(ClientPos: TPoint): integer;
var
  i, TabIx, VisiblePageInd: Integer;
begin
  if HandleAllocated then begin
    TabIx:=TWSCustomTabControlClass(WidgetSetClass).GetTabIndexAtPos(Self, ClientPos);
    // TabIx is the index in visible tabs because invisible tabs are removed
    //  from the native control. Calculate the real tab index here.
    VisiblePageInd:=-1;
    for i:=0 to PageCount-1 do
      if Page[i].TabVisible then begin
        Inc(VisiblePageInd);
        if VisiblePageInd = TabIx then begin
          Result := i;
          Break
        end
      end
  end else
    Result:=-1;
end;

Mantis conversion info:

• Mantis ID: 30343
• OS Build: 7 Professional
• Platform: Win32
• Version: 1.4.2
• Fixed in revision: r53950 (#f723ac55)
• Target version: 1.6.4