gui: fix properties tab background colour for windows build

main.go

@@ -10,7 +10,6 @@ import (
 	"github.com/pkg/browser"
 	"github.com/ying32/govcl/vcl"
 	"github.com/ying32/govcl/vcl/types"
-	"github.com/ying32/govcl/vcl/types/colors"
 )
 
 const (
@@ -187,8 +186,8 @@ func (f *TMainForm) OnFormCreate(sender vcl.IObject) {
 	f.propertiesBox.BorderSpacing().SetAround(MY_SPACING)
 	f.propertiesBox.SetAlign(types.AlClient) // fill remaining space
 	f.propertiesBox.SetReadOnly(true)
-	f.propertiesBox.SetEnabled(true)        // Need to leave it enabled so scrolling works
-	f.propertiesBox.SetColor(colors.ClForm) // 0x00f0f0f0
+	f.propertiesBox.SetEnabled(true) // Need to leave it enabled so scrolling works
+	f.propertiesBox.SetColor(vcl_default_tab_background())
 
 	f.propertiesBox.SetBorderStyle(types.BsNone)
 	f.propertiesBox.SetScrollBars(types.SsAutoVertical)

util_vcl.go

@@ -1,8 +1,11 @@
 package main
 
 import (
+	"runtime"
+
 	"github.com/ying32/govcl/vcl"
 	"github.com/ying32/govcl/vcl/types"
+	"github.com/ying32/govcl/vcl/types/colors"
 )
 
 const (
@@ -49,3 +52,13 @@ func vcl_menuseparator(parent *vcl.TMenuItem) *vcl.TMenuItem {
 
 	return s
 }
+
+func vcl_default_tab_background() types.TColor {
+	if runtime.GOOS == "windows" {
+		// Assuming that uxtheme is loaded
+		// @ref https://stackoverflow.com/a/20332712
+		return colors.ClBtnHighlight
+	} else {
+		return colors.ClBtnFace // 0x00f0f0f0
+	}
+}