Q156035: PRB: Control in Grid w/ When Returning .F. Passes Keys to Form
Article: Q156035
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b,5.0,6.0
Operating System(s):
Keyword(s):
Last Modified: 14-DEC-1999
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 6.0
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SYMPTOMS
========
Clicking on a grid column whose control's When() returns False allows focus to
be set to the grid column. In this state, keystrokes are passed to the form
containing the grid, calling the form's KeyPress event and actuating any hotkeys
on controls on the form.
WORKAROUND
==========
- Do not return False (.F.) from the control's When(), and conditionally issue
a KEYBOARD "{tab}" command in the control's GotFocus() to keep focus off
column.
- or -
- Conditionally issue a NODEFAULT in the KeyPress() method of the form.
STATUS
======
This behavior is by design.
MORE INFORMATION
================
This is normal behavior for the Grid object. This situation occurs because the
Grid object must change the record pointer before it can query columns or column
controls for Enabled = True. Once the record pointer is changed, the grid can't
go back because the grid does not save a previous record pointer.
Leaving the focus on the prior column before the user switches to the disabled
column or control may lead to problems when handling two special cases:
- When the grid is entered for the first time and there is no prior column.
- When DynamicCurrentControl is used and the current control for the previous
column gets set to a disabled control.
In addition, the grid must behave this way to accommodate the following special
case:
- If all the columns of a grid are disabled and the RecordMark and DeleteMark
properties are set to False, the user needs to have a way to change the
record pointer within the grid.
For more information about selection of grid columns with disabled controls, or
controls whose When() returns False, please see the following article in the
Microsoft Knowledge Base:
Q137963 PRB: Disabled Grid Controls Can Be Selected with Mouse
Steps to Reproduce Behavior
---------------------------
1. Run the following code from a program file:
* Start of sample program
PUBLIC oForm
oForm=CREATEOBJECT('form1')
oForm.SHOW
oForm.grid1.column1.ADDOBJECT('text2','txtTextbox')
oForm.grid1.column1.CURRENTCONTROL='text2'
oForm.grid1.column1.text2.VISIBLE=.T.
DEFINE CLASS form1 AS FORM
ADD OBJECT grid1 AS GRID WITH ;
COLUMNCOUNT = 2, ;
NAME = "Grid1"
ADD OBJECT command1 AS COMMANDBUTTON WITH ;
CAPTION = "\<Test", ;
HEIGHT=25, ;
TOP=205, ;
NAME = "Command1"
PROCEDURE LOAD
CREATE CURSOR test ( ctest c(10), ctest2 c(10) )
INSERT INTO test ( ctest) VALUES ( " ")
INSERT INTO test ( ctest) VALUES ( " ")
GO TOP
ENDPROC
PROCEDURE command1.VALID
WAIT WINDOW "Command button valid called" TIMEOUT 1
ENDPROC
ENDDEFINE
DEFINE CLASS txttextbox AS TEXTBOX
PROCEDURE WHEN()
RETURN RECNO()=1 && Returns .F. if not on first record
ENDPROC
ENDDEFINE
* End of sample program
2. Click the grid cell in the first column, second row of the grid.
3. Press the "t" (without the quotation marks) key. The Command button click
will be called by the "T" hotkey even though the grid has the focus.
Following are two examples of workarounds for this problem:
Method 1
--------
To prevent the column from getting focus:
1. Change the class definition for the textbox, removing the RETURN statement
from the When() and adding code to the GotFocus() method as follows:
DEFINE CLASS txtTextbox AS TEXTBOX
PROCEDURE GOTFOCUS()
IF RECNO()!=1 && Check for condition that was checked
&& in When()
KEYBOARD '{tab}'
ENDIF
ENDPROC
ENDDEFINE
2. Run the program, and click the grid cell in the first column, second row of
the grid. Note that the focus will not remain in the first column.
Method 2
--------
To intercept the KeyPress at the form level:
1. Add the following code in the KeyPress procedure of the class definition for
the Form:
PROCEDURE KeyPress
LPARAMETERS nKeyCode, nShiftAltCtrl
* Check to see if the ActiveControl is a Grid and that the
* ALT key was not pressed. If both of these are true, NODEFAULT
* will discard the keystroke. If the ALT key was pressed, you do
* want to use the keystroke to actuate any applicable hot-keyed
* control on the form.
IF this.ActiveControl.BaseClass = 'Grid' and nShiftAltCtrl != 4
NODEFAULT
ENDIF
ENDPROC
2. Run the program, and click the grid in the cell in the first column, second
row of the grid. Note that the focus will remain in the first column. Typing
"t" will not actuate the Command button but pressing the ALT+T keys will.
Additional query words: kbdse VFoxWin
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Keywords :
Technology : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600
Version : WINDOWS:3.0,3.0b,5.0,6.0
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