我对hello_widget这个项目做了适当的修改

//*****************************************************************************
//
// Forward reference to various widget structures.
//
//*****************************************************************************
extern tCanvasWidget g_sBackground;
extern tCanvasWidget g_sTop;
extern tCanvasWidget g_sMi;
extern tPushButtonWidget g_sPushBtn;



//*****************************************************************************
//
// Forward reference to the button press handler.
//
//*****************************************************************************
void OnButtonPress(tWidget *pWidget);

//*****************************************************************************
//
// The heading containing the application title.
//
//*****************************************************************************

//
//define the back ground on the top of the LCD as a canvas
//

Canvas(        g_sBackground,
                WIDGET_ROOT,
                0,&g_sTop,
                &g_sKitronix320x240x16_SSD2119,
                0,0,0,0,
                (CANVAS_STYLE_FILL|CANVAS_STYLE_OUTLINE),
                ClrBurlyWood,ClrRed,
                0,0,0,0,0);

               


//
//define the word on the top of the LCD as a canvas
//

Canvas( g_sTop,
                &g_sBackground,
                0,&g_sPushBtn,
                &g_sKitronix320x240x16_SSD2119,
                0,0,0,0,
                (CANVAS_STYLE_TEXT|CANVAS_STYLE_TEXT_HCENTER|CANVAS_STYLE_TEXT_OPAQUE),
                ClrBurlyWood,0,ClrRed,&g_sFontCm20i,"hello-widget",0,0);

               
               

//
//define a widget for the button
//

RectangularButton(        g_sPushBtn,
                                        &g_sTop,
                                        0,0,
                                        &g_sKitronix320x240x16_SSD2119,
                                        0,0,0,0,
                                        (PB_STYLE_FILL|PB_STYLE_OUTLINE|PB_STYLE_RELEASE_NOTIFY|PB_STYLE_TEXT|PB_STYLE_TEXT_OPAQUE),
                                        ClrBurlyWood,
                                        ClrCoral,
                                        ClrWhite,
                                        ClrRed,
                                        &g_sFontCm20i,
                                        "Show Hello!",
                                        0,0,0,0,OnButtonPress);
                                       
                                       

//
//define the cave for the Hello word
//

Canvas( g_sMi,
                &g_sPushBtn,
                0,0,
                &g_sKitronix320x240x16_SSD2119,
                0,0,0,0,
                (CANVAS_STYLE_TEXT|CANVAS_STYLE_TEXT_HCENTER|CANVAS_STYLE_TEXT_OPAQUE),
                0,0,ClrWhite,&g_sFontCm32,"Hello,world!",0,0);

tBoolean g_bHelloVisible = false;

               

void
OnButtonPress(tWidget *pWidget)
{
   
        g_bHelloVisible = !g_bHelloVisible;

    if(g_bHelloVisible)
    {
        //
        // Add the Hello widget to the tree as a child of the push
        // button.  We could add it elsewhere but this seems as good a
        // place as any.  It also means we can repaint from g_sPushBtn and
        // this will paint both the button and the welcome message.
        //
        WidgetAdd((tWidget *)&g_sPushBtn, (tWidget *)&g_sMi);

        //
        // Change the button text to indicate the new function.
        //
        PushButtonTextSet(&g_sPushBtn, "Hide Welcome");

        //
        // Repaint the pushbutton and all widgets beneath it (in this case,
        // the welcome message).
        //
        WidgetPaint((tWidget *)&g_sPushBtn);
    }
    else
    {
        //
        // Remove the Hello widget from the tree.
        //
        WidgetRemove((tWidget *)&g_sMi);

        //
        // Change the button text to indicate the new function.
        //
        PushButtonTextSet(&g_sPushBtn, "Show Welcome");
        //
        // Repaint the widget tree to remove the Hello widget from the
        // display.  This is rather inefficient but saves having to use
        // additional widgets to overpaint the area of the Hello text (since
        // disabling a widget does not automatically erase whatever it
        // previously displayed on the screen).
        //
        WidgetPaint(WIDGET_ROOT);
    }
}


int main(void)
{
        tContext sContext;
        //
        //set the clock for arm
        //

        SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

        //
        //Enable pins
        //

        PinoutSet();

        //
        //Init the LCD
        //

        Kitronix320x240x16_SSD2119Init();

        //
        //Init the sContext
        //

        GrContextInit(&sContext, &g_sKitronix320x240x16_SSD2119);

        //
    // Enable Interrupts
    //

    IntMasterEnable();

        //
    // Initialize the touch screen driver.
    //
    TouchScreenInit();

        //
    // Set the touch screen event handler.
    //
    TouchScreenCallbackSet(WidgetPointerMessage);

        //
    // Add the compile-time defined widgets to the widget tree.
    //



        g_sBackground.sBase.sPosition.sXMax        =GrContextDpyWidthGet(&sContext);
        g_sBackground.sBase.sPosition.sYMax =(GrContextDpyHeightGet(&sContext))/10;

        g_sTop.sBase.sPosition.sXMax =GrContextDpyWidthGet(&sContext);
        g_sTop.sBase.sPosition.sYMax =GrContextDpyHeightGet(&sContext)/10;

        g_sPushBtn.sBase.sPosition.sXMin =GrContextDpyWidthGet(&sContext)/5;
        g_sPushBtn.sBase.sPosition.sYMin =GrContextDpyHeightGet(&sContext)/4;
        g_sPushBtn.sBase.sPosition.sXMax =GrContextDpyWidthGet(&sContext)*4/5;
        g_sPushBtn.sBase.sPosition.sYMax =GrContextDpyHeightGet(&sContext)/2;

        g_sMi.sBase.sPosition.sXMin =GrContextDpyWidthGet(&sContext)/5;
        g_sMi.sBase.sPosition.sYMin =GrContextDpyHeightGet(&sContext)*6/10;
        g_sMi.sBase.sPosition.sXMax =GrContextDpyWidthGet(&sContext)*4/5;
        g_sMi.sBase.sPosition.sYMax =GrContextDpyHeightGet(&sContext)*9/10;

        WidgetAdd(WIDGET_ROOT, (tWidget *)&g_sBackground);

    //
    // Paint the widget tree to make sure they all appear on the display.
    //
    WidgetPaint(WIDGET_ROOT);

    //
    // Loop forever, processing widget messages.
    //
    while(1)
    {
        //
        // Process any messages from or for the widgets.
        //
        WidgetMessageQueueProcess();
    }
}


但是在我按键让hello消失的时候，无法消失，这是为什么呢？麻烦路过的大哥帮帮忙！ 此帖出自小平头技术问答