Correct bug in the wxSpinCtrlGeneric sub-controls resizing.

The code in DoMoveWindow() didn't account for the margin and made the text
control part of the window too large resulting in the truncation of the spin
button.

Simply remember to take margin into account when computing the text width.

See #12767.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66443 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/spinctlg.cpp

@@ -270,7 +270,7 @@ void wxSpinCtrlGenericBase::DoMoveWindow(int x, int y, int width, int height)
     // position the subcontrols inside the client area
     wxSize sizeBtn = m_spinButton->GetSize();
 
-    wxCoord wText = width - sizeBtn.x;
+    wxCoord wText = width - sizeBtn.x - MARGIN;
     m_textCtrl->SetSize(x, y, wText, height);
     m_spinButton->SetSize(x + wText + MARGIN, y, wxDefaultCoord, height);
 }