wxWindows 2 FAQ: Questions common to all platforms
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See also top-level FAQ page.
List of questions in this category
All windows and controls in wxWindows programs are created using new
but you shouldn't use delete to free them. This doesn't result
in memory leaks because wxWindows takes care of this: all objects derived from
wxWindow will be deleted automatically by the library when the corresponding
real, on screen, window is destroyed. Thus, the top level window objects are
deleted when you call Close() or Destroy() and all the child
windows are deleted just before the parent window is. More details about the
top level windows can be found in the ``Window deletion overview'' in
the manual.
wxWindows also automatically deletes some other kind of the objects, notably
the sizer or constraint associated with the window -- this happens just before
the window itself is deleted. The sizers, in turn, delete their child sizers
automatically as well so in a typical situation you don't have to worry
about freeing the sizers you create. Note, however, that if you
Remove() a sizer from the window, it isn't automatically deleted
any more and you are responsable for doing this.
Please look at the event wxWindows sample source code, it shows how to
do this among other things. Note that the way custom events are defined has
changed in wxWindows 2.3.1 as compared to the previous releases.
Unfortunately in the current wxWindows version (2.4.0 as of this writing) this
is not possible: the TAB order of the control (that is, the order in which the
controls gain focus when the user repeatedly presses the <TAB>
key) is fixed and is the same as the order of the controls creation.
Changing this should become possible in future versions of wxWindows as soon as
we come up with a nice API for this feature.
First of all, _T() is exactly the same as wxT() (it exists
only because it should be more familiar to Windows programmers) which reduces
the problem of choosing among the macros to use somewhat.
Here is some pseudo-code for choosing the macro to use between the remaining
possibilities, that is whether to use wxT(), use _() or not
use any of them:
if ( string should be translated )
use _("string")
else if ( string should be in Unicode in Unicode build )
use wxT("string")
else
just use "string" normally
Note that if you don't care about Unicode at all, you don't have to use
wxT() at all. On the contrary, if you do, note that _()
takes care of it internally so if you use it your code will compile in both
the ANSI and Unicode builds.
Please see the description of these macros in the manual for more details.
Pressing Esc will close the dialog if and only if it has a button
with wxID_CANCEL id.
These message boxes are probably due to calls to wxLogError() or
other log functions from wxWindows code. To completely suppress them you
may use wxLogNull class, please see the manual for details. Do note, however,
that a better solution is to avoid the error in the first place as suppressing
these error message might hide other, important, ones.
This topic is covered in the technical note Writing installers.