Delphi中delete函数，tabstop，ItemIndex，Down属性

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Delete procedure
Removes a substring from a string.


Unit
System


Category
string handling routines
procedure Delete(var S: string; Index, Count:Integer);


Description
Delete removes a substring of Count characters from string S starting with S[Index]. S is a string-type variable. Index and Count are integer-type expressions. 
If index is larger than the length of the S or less than 1, no characters are deleted.
If count specifies more characters than remain starting at the index, Delete removes the rest of the string. If count is less than 0, no characters are deleted.
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TWinControl.TabStop
Determines if the user can tab to a control.


property TabStop: Boolean;


Description
Use the TabStop to allow or disallow access to the control using the Tab key.
If TabStop is True, the control is in the tab order. If TabStop is False, the control is not in the tab order and the user can't press the Tab key to move to the control. 


Note: TabStop is not meaningful for a form unless the form assigns another form to be its parent.
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TCustomListBox.ItemIndex
Specifies the ordinal number of the selected item in the list box抯 item list.


property ItemIndex: Integer;


Description


Use ItemIndex to select an item at runtime. Set the value of ItemIndex to the index of the item to be selected. The ItemIndex of the first item in the list box is 0. If no item is selected, the value is -1, which is the default value unless MultiSelect is True.


If the value of the MultiSelect property is True the user can select more than one item in the list box. In this case, the ItemIndex value is the index of the selected item that has focus. If MultiSelect is True, ItemIndex defaults to 0. 
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TSpeedButton.Down
Specifies whether the button is selected (down) or unselected (up).


property Down: Boolean;


Description


Read Down to determine whether a speed button is selected. The Down property only applies if the GroupIndex property of the button is nonzero.
When GroupIndex is greater than 0, set Down to True to select a button. When the user clicks on a button in the unselected (up) state, the button is selected and Down is set to True. When the user clicks on a button in the selected (down) state, if Caption is True, the button becomes unselected and Down is set to False.
SpeedButton可以设计成一组互斥的选项，只要选中若干个SpeedButton，并将它们的GroupIndex属性赋予相同的值即可。
SpeedButton.Down 为True时SpeedButton为按下状态，否则为松开状态
SpeedButton.Flat 为True时，当鼠标指向时才如按钮般凸出来，为false时无这效果
SpeedButton.GroupIndex 若值大于0，则GroupIndex相同的若干SpeedButton将协同工作，在同一时间里，它们中只有一个可处于按下状态


fmFund,fmAsset,fmCombi,fmMarket,fmStockType,fmStockCode,fmQDStockCode,
fmEntrustDirection,fmStockHolder,fmSeat,fmDictionary,fmOperator,fmTradeRival
fmAccountGroup,fmLayout
对于fm开头的且不是数据字典形式的，通过调用Refresh函数可以读物数据库数据...
At design time, specify which button in a group is the initially selected button by setting the Down property of the selected button to True.


Note: When GroupIndex is 0, buttons do not remain in the selected state when clicked.