procedure CreateParams(var Params: TCreateParams); override;
参数定义如下：

TCreateParams = record
Caption: PChar;
Style: DWORD;
ExStyle: DWORD;
X, Y: Integer;
Width, Height: Integer;
WndParent: HWnd;
Param: Pointer;
WindowClass: TWndClass;
WinClassName: array[0..63] of Char;
end;

其中Style的取值：
Window Styles

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The following styles can be specified wherever a window style is required. After
the control has been created, these styles cannot be modified, except as noted.

Constants

WS_BORDER
Creates a window that has a thin-line border.

WS_CAPTION
Creates a window that has a title bar (includes the WS_BORDER style).

WS_CHILD
Creates a child window. A window with this style cannot have a menu bar. This st
yle cannot be used with the WS_POPUP style.

WS_CHILDWINDOW
Same as the WS_CHILD style.

WS_CLIPCHILDREN
Excludes the area occupied by child windows when drawing occurs within the paren
t window. This style is used when creating the parent window.

WS_CLIPSIBLINGS
Clips child windows relative to each other; that is, when a particular child win
dow receives a WM_PAINT message, the WS_CLIPSIBLINGS style clips all other overl
apping child windows out of the region of the child window to be updated. If WS_
CLIPSIBLINGS is not specified and child windows overlap, it is possible, when dr
awing within the client area of a child window, to draw within the client area o
f a neighboring child window.

WS_DISABLED
Creates a window that is initially disabled. A disabled window cannot receive in
put from the user. To change this after a window has been created, use EnableWin
dow.

WS_DLGFRAME
Creates a window that has a border of a style typically used with dialog boxes.
A window with this style cannot have a title bar.

WS_GROUP
Specifies the first control of a group of controls. The group consists of this first control and all controls defined after it, up to the next control with the WS_GROUP style. The first control in each group usually has the WS_TABSTOP style so that the user can move from group to group. The user can subsequently change the keyboard focus from one control in the group to the next control in the group by using the direction keys.
You can turn this style on and off to change dialog box navigation. To change th
is style after a window has been created, use SetWindowLong.

WS_HSCROLL
Creates a window that has a horizontal scroll bar.

WS_ICONIC
Creates a window that is initially minimized. Same as the WS_MINIMIZE style.

WS_MAXIMIZE
Creates a window that is initially maximized.

WS_MAXIMIZEBOX
Creates a window that has a maximize button. Cannot be combined with the WS_EX_C
ONTEXTHELP style. The WS_SYSMENU style must also be specified.

WS_MINIMIZE
Creates a window that is initially minimized. Same as the WS_ICONIC style.

WS_MINIMIZEBOX
Creates a window that has a minimize button. Cannot be combined with the WS_EX_C
ONTEXTHELP style. The WS_SYSMENU style must also be specified.

WS_OVERLAPPED
Creates an overlapped window. An overlapped window has a title bar and a border.
Same as the WS_TILED style.

WS_OVERLAPPEDWINDOW
Creates an overlapped window with the WS_OVERLAPPED, WS_CAPTION, WS_SYSMENU, WS_
THICKFRAME, WS_MINIMIZEBOX, and WS_MAXIMIZEBOX styles. Same as the WS_TILEDWINDO
W style.

WS_POPUP
Creates a pop-up window. This style cannot be used with the WS_CHILD style.

WS_POPUPWINDOW
Creates a pop-up window with WS_BORDER, WS_POPUP, and WS_SYSMENU styles. The WS_
CAPTION and WS_POPUPWINDOW styles must be combined to make the window menu visib
le.

WS_SIZEBOX
Creates a window that has a sizing border. Same as the WS_THICKFRAME style.

WS_SYSMENU
Creates a window that has a window menu on its title bar. The WS_CAPTION style m
ust also be specified.

WS_TABSTOP
Specifies a control that can receive the keyboard focus when the user presses th
e TAB key. Pressing the TAB key changes the keyboard focus to the next control w
ith the WS_TABSTOP style.
You can turn this style on and off to change dialog box navigation. To change th
is style after a window has been created, use SetWindowLong.

WS_THICKFRAME
Creates a window that has a sizing border. Same as the WS_SIZEBOX style.

WS_TILED
Creates an overlapped window. An overlapped window has a title bar and a border.
Same as the WS_OVERLAPPED style.

WS_TILEDWINDOW
Creates an overlapped window with the WS_OVERLAPPED, WS_CAPTION, WS_SYSMENU, WS_
THICKFRAME, WS_MINIMIZEBOX, and WS_MAXIMIZEBOX styles. Same as the WS_OVERLAPPED
WINDOW style.

WS_VISIBLE
Creates a window that is initially visible.
This style can be turned on and off by using ShowWindow or SetWindowPos.

WS_VSCROLL
Creates a window that has a vertical scroll bar.