&&主程序.prg
SET TALK OFF
SET ECHO OFF
SET DATE TO ansi
SET ESCAPE ON
SET SAFETY OFF
SET EXACT OFF
SET DELETED ON
SET CENTURY ON
CLOSE ALL
CLEAR ALL
&&_screen.Visible= .F.  &&在config.fpw中用SCREEN=OFF代替了
PUBLIC currUser &&,userPerm 登录用户权限
PUBLIC myDrv,myDir,myProgPath &&当前程序所在盘和所在路径
myDrv=SYS(5)
myDir=SYS(2003)
myProgPath=myDrv+myDir
SET DEFAULT TO &myProgPath
DO 登录验证.prg
READ events

DEFINE CLASS exitBtn as CommandButton 
    caption="退　出"
    
    PROCEDURE click
        RELEASE thisform 
    ENDPROC 
ENDDEFINE 

＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋

&&登录验证.prg
CLEAR ALL 

loginForm=CREATEOBJECT("myForm")
    WITH loginForm
        .caption="欢迎登录材料管理系统"
        .autoCenter=.t.
        .width=300
        .height=200
        .titleBar=0
        .showWindow=2
        .picture="登录背景.bmp"
        .icon="logo.ico"
        .controlBox=.f.        
        .show
    ENDWITH
READ EVENTS
CLEAR ALL 
RETURN 

DEFINE CLASS myForm as Form 
    ADD OBJECT cmdExit as exitBtn WITH top=168,left=228
    
    
ENDDEFINE

两个问题：
一、公共的类，可以这样写在主程序中吗？
二、为什么提示“属性showwindow只读”？
请各位老师指导一下

READ EVENTS 要与 CLEAR EVENTS 配对使用。
READ EVENTS 进入一个消息循环
CLEAR EVENTS 退出这个消息循环

DO 登录验证.prg
**READ events 这句不要

&&登录验证.prg
CLEAR ALL

loginForm=CREATEOBJECT("myForm")
    WITH loginForm
        .caption="欢迎登录材料管理系统"
        .autoCenter=.t.
        .width=300
        .height=200
        .titleBar=0
        .showWindow=2
        .picture="登录背景.bmp"
        .icon="logo.ico"
        .controlBox=.f.        
        .show
    ENDWITH
READ EVENTS
CLEAR ALL
RETURN

DEFINE CLASS myForm as Form
    ADD OBJECT cmdExit as exitBtn WITH top=168,left=228
   
    PROCEDURE Unload
        CLEAR EVENTS
    ENDPROC
ENDDEFINE

SET TALK OFF
SET ECHO OFF
SET DATE TO ansi
SET ESCAPE ON
SET SAFETY OFF
SET EXACT OFF
SET DELETED ON
SET CENTURY ON
CLOSE ALL
CLEAR ALL
&&_screen.Visible= .F.  &&在config.fpw中用SCREEN=OFF代替了
PUBLIC currUser &&,userPerm 登录用户权限
PUBLIC myDrv,myDir,myProgPath &&当前程序所在盘和所在路径
myDrv=SYS(5)
myDir=SYS(2003)
myProgPath=myDrv+myDir
SET DEFAULT TO &myProgPath
DO 登录验证.prg
&&READ events

DEFINE CLASS showWindowForm as Form 
    showWindow=2
    
    PROCEDURE destroy
        CLEAR EVENTS 
    ENDPROC 
    
ENDDEFINE


DEFINE CLASS exitBtn as CommandButton 
    caption="退　出"
    
    PROCEDURE click
        RELEASE thisform 
    ENDPROC 
ENDDEFINE 

＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋

&&登录验证.prg
CLEAR ALL 

loginForm=CREATEOBJECT("logForm")
    WITH loginForm
        .caption="欢迎登录材料管理系统"
        .autoCenter=.t.
        .width=300
        .height=200
        .titleBar=0
        &&.showWindow=2  写在这里不行
        .picture="登录背景.bmp"
        .icon="logo.ico"
        .controlBox=.f.        
        .show
    ENDWITH
READ EVENTS
CLEAR ALL 
RETURN 

DEFINE CLASS logForm as showWindowForm
    ADD OBJECT cmdExit as exitBtn WITH top=168,left=228
    
ENDDEFINE

这样解决的

不要每个模块都CLEAR ALL啊，那样会清楚掉全局数据的。

一、所有的代码都可以写在一个PRG文件中，分开写只是出于程序员组织代码的需要，並非语言要求。
二、窗口的运行模式不可能临时改变，是事物本身的性质决定制作Form类的时候把屬性ShowWindow设置为只读。