using icons instead of text for the min/max icon,

the min icon looks not good

ChannelListWidget.cpp

@@ -3,6 +3,7 @@
 #include <Windows.h>
 #include <qboxlayout.h>
 #include <QFile>
+#include <QApplication>
 
 ChannelTree::ChannelTree(ChannelListWidget * widget, QWidget *parent)
 	: QTreeWidget(parent)
@@ -102,6 +103,23 @@ ChannelListWidget::ChannelListWidget(QWidget *parent)
 {
 	m_state = full;
 
+	QIcon myIcon = QApplication::style()->standardIcon(QStyle::SP_TitleBarMinButton);
+	auto avalSize = myIcon.availableSizes();
+	for (auto& singleSize : avalSize) {
+		QImage tempImage = myIcon.pixmap(singleSize).toImage();
+		tempImage.invertPixels();
+		m_minIcon.addPixmap(QPixmap::fromImage(std::move(tempImage)));
+	}
+
+	myIcon = QApplication::style()->standardIcon(QStyle::SP_TitleBarMaxButton);
+	avalSize = myIcon.availableSizes();
+	for (auto& singleSize : avalSize) {
+		QImage tempImage = myIcon.pixmap(singleSize).toImage();
+		tempImage.invertPixels();
+		m_maxIcon.addPixmap(QPixmap::fromImage(std::move(tempImage)));
+	}
+
+
 	setAttribute(Qt::WA_TranslucentBackground);
 	setWindowFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint | Qt::SplashScreen);
 	move(320, 200);
@@ -113,7 +131,7 @@ ChannelListWidget::ChannelListWidget(QWidget *parent)
 	layout->setSpacing(0);
 
 	m_button = new QPushButton(this);
-	m_button->setText("-");
+	m_button->setIcon(m_minIcon);
 	connect(m_button, &QPushButton::pressed, this, &ChannelListWidget::buttonPressed);
 	QFile style("plugins\\qtTsOverlay\\button.styl");
 	style.open(QIODevice::ReadOnly);
@@ -148,12 +166,12 @@ void ChannelListWidget::buttonPressed()
 	if (m_state == full)
 	{
 		m_state = minimum;
-		m_button->setText("O");
+		m_button->setIcon(m_maxIcon);
 	}
 	else
 	{
 		m_state = full;
-		m_button->setText("-");
+		m_button->setIcon(m_minIcon);
 	}
 
 	emit treeStateChanged(m_state);

ChannelListWidget.h

@@ -5,6 +5,7 @@
 #include <QSizeGrip>
 #include <QLabel>
 #include <QPushButton>
+#include <QIcon>
 
 enum TreeState {
 	full,
@@ -67,6 +68,8 @@ private:
 	QSizeGrip *m_grip;
 	Background *m_background;
 	QPushButton* m_button;
+	QIcon m_minIcon;
+	QIcon m_maxIcon;
 
 private slots:
 	void buttonPressed();