问题描述：

当QToolbutton 用于QToolBar时用 setIconSize()设置图标大小没有作用；

解决方法：

QToolbutton按钮设置图标大小，根据帮助手册查询如下：
The button’s look and dimension is adjustable with setToolButtonStyle() and setIconSize(). When used inside a QToolBar in a QMainWindow, the button automatically adjusts to QMainWindow’s settings (see QMainWindow::setToolButtonStyle() and QMainWindow::setIconSize()). Instead of an icon, a tool button can also display an arrow symbol, specified with arrowType.

当QToolButton被设置为QToolBar时，此时调用** setIconSize() **函数设置无法设置图标大小,此时应该设置QMainWindow的setIconSize()才能进行设置大小；具体实现代码如下：

bool MainWindowUI::makeToolButton(QToolButton*& toolbutton, QWidget* parent, QString tip, QString icon){bool ret = true;toolbutton = new QToolButton();if(toolbutton != NULL){toolbutton->setParent(parent);toolbutton->setText(tip);toolbutton->setIcon(QIcon(QPixmap(icon)));this->setIconSize(QSize(TOOLBUTTON_ICON_SIZE_W,TOOLBUTTON_ICON_SIZE_H));	//设置图标大小；toolbutton->setFont(QFont(TOOLBUTTON_FONT, TOOLBUTTON_FONT_SIZE, TOOLBUTTON_FONT_WEIGHT));toolbutton->setToolButtonStyle(Qt::ToolButtonTextUnderIcon);}else{delete toolbutton;toolbutton = NULL;ret = false;}return ret;}