Some changes from LazVTV

Author: salvadorbs

Source/VirtualTrees.pas

@@ -6134,6 +6134,8 @@ function TVirtualTreeHintWindow.CalcHintRect(MaxWidth: Integer; const AHint: str
               DoPaintText(Node, Self.Canvas, Column, ttNormal);
           //force the default hint font color
           Canvas.Font.Color := Screen.HintFont.Color;
+          if Canvas.Font.Color = clDefault then
+            Canvas.Font.Color := clInfoText;
         end;
 
         //let THintWindow do the job
@@ -8331,7 +8333,7 @@ procedure TVirtualTreeColumns.DrawButtonText(DC: HDC; Caption: String; Bounds: T
     else
       TextColor := FHeader.Treeview.FColors.HeaderFontColor;
     if TextColor = clDefault then
-      TextColor := clBtnText;
+      TextColor := FHeader.Treeview.GetDefaultColor(dctFont);
     SetTextColor(DC, ColorToRGB(TextColor));
     DrawText(DC, PChar(Caption), Length(Caption), Bounds, DrawFormat);
   end;
@@ -9521,8 +9523,13 @@ procedure TVirtualTreeColumns.PaintHeader(TargetCanvas: TCanvas; R: TRect; const
               ColImageInfo.Index := GetCheckImage(nil, FCheckType, FCheckState, IsEnabled);
               ColImageInfo.XPos := GlyphPos.X;
               ColImageInfo.YPos := GlyphPos.Y;
+              if ColImageInfo.Images <> nil then begin
               w := ColImageInfo.Images.Width;
               h := ColImageInfo.Images.Height;
+              end else begin
+                w := 0;
+                h := 0;
+              end;
               PaintCheckImage(TargetCanvas, ColImageInfo, False);
             end;
           end;
@@ -9627,6 +9634,9 @@ procedure TVirtualTreeColumns.PaintHeader(TargetCanvas: TCanvas; R: TRect; const
     // Use shortcuts for the images and the font.
     Images := FHeader.FImages;
     Font := FHeader.FFont;
+    if Font.Color = clDefault then
+      Font.Color := FHeader.Treeview.GetDefaultColor(dctFont);
+
     {$IF LCL_FullVersion >= 2000000}
     if Images <> nil then
       ImagesRes := Images.ResolutionForPPI[FHeader.ImagesWidth, Font.PixelsPerInch, Header.TreeView.GetCanvasScaleFactor];
@@ -14481,7 +14491,7 @@ procedure TBaseVirtualTree.PrepareBitmaps(NeedButtons, NeedLines: Boolean);
 
   {$ifdef ThemeSupport}
   {$ifdef Windows}
-    if Theme <> 0 then
+    if tsUseThemes in FStates then
       CloseThemeData(Theme);
   {$endif}
   {$endif ThemeSupport}
@@ -22767,7 +22777,7 @@ procedure TBaseVirtualTree.HandleMouseDown(var Message: TLMMouse; var HitInfo: T
   else // No MultiSelect, hence we can start a drag anywhere in the row.
     FullRowDrag := toFullRowDrag in FOptions.FMiscOptions;
 
-  IsHeightTracking := (Message.Msg = LM_LBUTTONDOWN) and
+  IsHeightTracking := (Message.Msg = WM_LBUTTONDOWN) and
                       (hiOnItem in HitInfo.HitPositions) and
                       ([hiUpperSplitter, hiLowerSplitter] * HitInfo.HitPositions <> []);
 
@@ -24448,10 +24458,10 @@ procedure TBaseVirtualTree.PaintNodeButton(Canvas: TCanvas; Node: PVirtualNode;
   IsHot: Boolean;
   {$ifdef Windows}
   Theme: HTHEME;
-  {$endif}
   Glyph: Integer;
   State: Integer;
   Pos: TRect;
+  {$endif}
 
 begin
   IsHot := (toHotTrack in FOptions.FPaintOptions) and (FCurrentHotNode = Node) and FHotNodeButtonHit;
@@ -24464,11 +24474,11 @@ procedure TBaseVirtualTree.PaintNodeButton(Canvas: TCanvas; Node: PVirtualNode;
 
   if tsUseExplorerTheme in FStates then
   begin
+    {$ifdef Windows}
     Glyph := IfThen(IsHot, TVP_HOTGLYPH, TVP_GLYPH);
     State := IfThen(vsExpanded in Node.States, GLPS_OPENED, GLPS_CLOSED);
     Pos := Rect(XPos, R.Top + ButtonY, XPos + FPlusBM.Width, R.Top + ButtonY + FPlusBM.Height);
 
-    {$ifdef Windows}
     Theme := OpenThemeData(Handle, 'TREEVIEW');
     DrawThemeBackground(Theme, Canvas.Handle, Glyph, State, Pos, nil);
     CloseThemeData(Theme);
@@ -33635,7 +33645,7 @@ procedure TCustomVirtualStringTree.InitializeTextProperties(var PaintInfo: TVTPa
       end;
     end;
     if Canvas.Font.Color = clDefault then
-      Canvas.Font.Color := clWindowText;
+      Canvas.Font.Color := GetDefaultColor(dctFont);
   end;
 end;
 
@@ -33749,6 +33759,8 @@ procedure TCustomVirtualStringTree.PaintStaticText(const PaintInfo: TVTPaintInfo
   with PaintInfo do
   begin
     Canvas.Font := Font;
+    if Font.Color = clDefault then
+      Canvas.Font.Color := GetDefaultColor(dctFont);
     if toFullRowSelect in FOptions.FSelectionOptions then
     begin
       if Node = FDropTargetNode then
@@ -33766,6 +33778,8 @@ procedure TCustomVirtualStringTree.PaintStaticText(const PaintInfo: TVTPaintInfo
           else
             Canvas.Font.Color := FColors.NodeFontColor;
         end;
+      if Canvas.Font.Color = clDefault then
+        Canvas.Font.Color := GetDefaultColor(dctFont);
     end;
 
     DrawFormat := DT_NOPREFIX or DT_VCENTER or DT_SINGLELINE;
@@ -34210,6 +34224,7 @@ function TCustomVirtualStringTree.DoShortenString(Canvas: TCanvas; Node: PVirtua
   Done: Boolean;
 
 begin
+  Result := '';
   Done := False;
   if Assigned(FOnShortenString) then
     FOnShortenString(Self, Canvas, Node, Column, S, Width, Result, Done);