Avoid automatically closing parent frame if a child dialog was closed.

This counterintuitive behaviour could happen when a dialog of a frame
returning false from its ShouldPreventAppExit() was closed: if there were no
other TLWs in the application, then the parent frame could be closed as well,
even if this clearly shouldn't happen.

See #15880.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75630 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Ensure that the help viewer keeps running as long as its main frame is opened.

Do prevent the app from exiting when the help frame is shown in the special
case of the help viewer application where the default behaviour of exiting the
application when only the help window remains open is inappropriate and
results in unexpected program exit if we open and then close any dialog, e.g.
from the help frame toolbar.

Even though the previous commit actually already fixed the problem in the
current code, still apply this fix as well, just in case we can (or could, in
the future) should any dialogs with NULL parent in this program.

Closes #15880.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75631 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
wxWindow::SetWindowVariant() does do something under ports other than wxOSX.

Document that this function adjusts the window font size under non-OS X
systems and explain why it should still be used instead of changing the font
size directly.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75632 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
avoid crash with GTK3 when deleting an item, closes #15786

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75639 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix possible crash in TAR header parsing code.

Check that the iterator is valid before using its value, otherwise the
validity check was useless.

Closes #15888.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75641 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix setting fonts and colours for wxToggleButton with bitmaps in wxGTK.

Apply the fixes of r54138 to wxToggleButton too, the problem of #3939 was not
specific to just plain wxButtons.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75643 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix best size calculation with GTK3
GTK3 reports preferred size of hidden widgets as zero.
see #15896


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75668 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
restrict fix from r75668 to GTK3 only, as it might cause flickering

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75670 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Russian translations update from Dmitry Levichev.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75671 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775