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Report From: Delphi-BCB/VCL/Styles [ Add a report in this area ]

Report #: 103962

Status: Closed

Disabling a button from its OnClick handler fails to update the buttons's visual appearance

Project: Delphi

Build #: 16.0.4429.46931

Version: 16.4

Submitted By: David Heffernan

Report Type: Crash / Data loss / Total failure

Date Reported: 3/6/2012 4:27:36 AM

Severity: Critical / Show Stopper

Last Updated: 9/5/2012 7:57:23 PM

Platform: All versions

Internal Tracking #: 26402

Resolution: Fixed (Resolution Comments)

Resolved in Build: : 17.0.4625.53395

Duplicate of: None

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Description

When using VCL styles, setting the Enabled property of a TButton to False from that button's OnClick handler fails to update the button's visual appearance.

The button is disabled, it can not be clicked. However it still looks like it is enabled. Setting a the Enabled property of a different button (i.e. not the button whose OnClick handler is running) does modify the visuals.

Steps to Reproduce:

Reproduce the problem with the attached project.

The erroneous code is in the Paint method of  TButtonStyleHook:

if FPressed then
  Details := StyleServices.GetElementDetails(tbPushButtonPressed)
else if MouseInControl  then //this condition is triggered even if the button is disabled
  Details := StyleServices.GetElementDetails(tbPushButtonHot)
else if Focused then //this condition is triggered even if the button is disabled
  Details := StyleServices.GetElementDetails(tbPushButtonDefaulted)
else if Control.Enabled then
  Details := StyleServices.GetElementDetails(tbPushButtonNormal)
else
  Details := StyleServices.GetElementDetails(tbPushButtonDisabled);

This code should read:

if not Control.Enabled then
  Details := StyleServices.GetElementDetails(tbPushButtonDisabled);
else if FPressed then
  Details := StyleServices.GetElementDetails(tbPushButtonPressed)
else if MouseInControl then
  Details := StyleServices.GetElementDetails(tbPushButtonHot)
else if Focused then
  Details := StyleServices.GetElementDetails(tbPushButtonDefaulted)
else
  Details := StyleServices.GetElementDetails(tbPushButtonNormal)

Workarounds

If the button's window handle is recreated this is sufficient to produce the correct visuals:

Button1.Perform(CM_RECREATEWND, 0, 0);

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