[ wxwindows-Bugs-1801928 ] wxSizer::SetSizeHints/wxSizer::Fit can fail to resize window

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Bugs item #1801928, was opened at 2007-09-25 12:54
Message generated for change (Comment added) made by vadz
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Category: wxMSW specific
Group: Platform specific
Status: Open
Resolution: None
>Priority: 6
Private: No
Submitted By: Roger James (rogerjames99)
>Assigned to: Vadim Zeitlin (vadz)
Summary: wxSizer::SetSizeHints/wxSizer::Fit can fail to resize window

Initial Comment:
wxSizer::SetSizeHints calls wxSizer::Fit followed by wxWindow::SetSizeHints. wxSizer::Fit will recalcualte the new min and max sizes but not set them as size hints in the target window. It will then call wxWindow::SetSize, on the windows platfom this results in a WM_GETMINMAXINFO message being processed inline by a call to wxWindowMSW::HandleGetMinMaxInfo, this will be processed using the old size hints for the window as they have not yet been set by wxWindow::SetSizeHints. This means if these values are not default they will be used to limit the bounds of the current SetSize operation. The most obvious manifestation of this is when widgets have been removed or hidden from a dialog box causing its minimum size to shrink. A single call to wxSizer::SetSizeHints will not shrink the dialog box. Two consecutive calls are needed, or the call preceded by a call to wxWindow::SetMinSize(wxDefaultSize). This is beyond my competence to suggest a patch for (I have never really understood
  sizers!). Setting the size hints to default within wxSizer::Fit seems a bit drastic as one might rightly assume that this should work within the constraints of the current size hints. Maybe they should be set to default at the top of the wxSizer::SetSizeHints code. Another approach may be to document the work round in the appropriate places.

Roger

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>Comment By: Vadim Zeitlin (vadz)
Date: 2008-02-12 03:00

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We really, really need to do something about this. The same bug also
appears in wx code itself (in wxCollapsiblePane).

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