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<b>wxWidgets 2 for GTK FAQ</b>
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<P>

See also <a href="faq.htm">top-level FAQ page</a>
and <a href="faqunx.htm">Unix FAQ page</a>.
<hr>
<h3>List of questions in this category</h3>

<ul>
<li><a href="#wxgtk">What is wxWidgets 2 for GTK+?</a></li>
<li><a href="#locale">Why doesn&#39;t reading floating point numbers work when using wxWidgets?</a></li>
<li><a href="#gnome">Does wxGTK have GNOME support?</a></li>
<li><a href="#redhat">Warning about GTK libraries supplied with RedHat</a></li>
<li><a href="#bincompat">What range of Intel Linux platforms will a given application binary be usable on?</a></li>
<li><a href="#static">Can I statically link the GTK+ library?</a></li>
<li><a href="#charinframe">Why does my simple program using <tt>EVT_CHAR</tt> not work?</a></li>
<li><a href="#debugging">How do I trace the cause of an X11 error such as BadMatch?</a></li>
</ul>

<hr>

<h3><a name="wxgtk">What is wxWidgets 2 for GTK?</a></h3>

wxWidgets 2 for GTK is a port of wxWidgets to the <a href="http://www.gimp.org/gtk" target=_top>GTK+ toolkit</a>,
which is freely available for most flavours of Unix with X. wxWidgets 2 for GTK is
often abbreviated to wxGTK. wxGTK has a separate home page <a href="http://www.freiburg.linux.de/~wxxt" target=_top>here</a>.
<P>

<h3><a name="locale">Why doesn&#39;t reading floating point numbers work when using wxWidgets?</a></h3>

If your program reads the floating point numbers in the format <tt>123.45</tt>
from a file, it may suddenly start returning just <tt>123</tt> instead of the
correct value on some systems -- which is all the more mysterious as the same
code in a standalone program works just fine.

<p>
The explanation is that GTK+ changes the current locale on program startup. If
the decimal point character in the current locale is not the period (for
example, it is comma in the French locale), all the standard C functions won&#39;t
recognize the numbers such as above as floating point ones any more.

<p>
The solution is to either use your own function for reading the floating point
numbers (probably the best one) or to call <tt>setlocale(LC_NUMERIC, "C")</tt>
before reading from file and restore the old locale back afterwards if needed.

<h3><a name="gnome">Does wxGTK have GNOME support?</a></h3>

Currently wxGTK does not have any features that would involve dependence on any desktop
environment&#39;s libraries, so it can work on GNOME, KDE and with other window managers
without installation hassles. Some GNOME and KDE integration features are file based, and
so may be added without dependence on libraries. Other features may be supported in the
future, probably as a separate library.
<P>

<h3><a name="redhat">Warning about GTK+ libraries supplied with RedHat</a></h3>

It seems that some versions of RedHat include a badly patched version of GTK+ (not wxGTK)
which causes some trouble with wxWidgets&#39; socket code. Common symptoms are that when
a client tries to establish a connection to an existing server which refuses the request,
the client will get notified twice, first getting a LOST event and then a CONNECT event.
This problem can be solved by updating GTK with an official distribution of the library.
<P>

<h3><a name="bincompat">What range of Intel Linux platforms will a given application binary be usable on?</h3>

Robert Roebling replies:<P>

&#34;The important thing is the libc version that your app
is linked against. The most recent version is 2.2.5
and programs linked against it will not run with version
2.1.X so that you will fare best if you compile your app
on a 2.1.X system. It will then run on practically all
Linux distros (if you link you app statically against
the image libraries and std C++ lib).&#34;
<P>

<h3><a name="#static">Can I statically link the GTK+ library?</a></h3>

No, this is not possible. It leads to crashes in GTK+.
<P>

<h3><a name="#charinframe">Why does my simple program using
<tt>EVT_CHAR</tt> not work?</a></h3>

In wxGTK, the frames never get focus and so can never receive <tt>CHAR</tt>
nor <tt>KEY</tt> events so an <tt>EVT_CHAR</tt> handler for a frame will be
never called. To receive these events, you should create a <tt>wxPanel</tt>
inside the frame and register the key event handlers for the panel, not the
frame.

<p>

<h3><a name="#debugging">How do I trace the cause of an X11 error such as BadMatch?</h3>

When a fatal X11 error occurs, the application quits with no stack trace.
To find out where the problem is, put a breakpoint on g_log (<tt>b g_log</tt>
in gdb).

<p>

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Commit	Line	Data
ce3ed50d JS	1	<HTML>
	2
	3	<HEAD>
c140b7e7	4	<TITLE>wxWidgets 2 for GTK FAQ</TITLE>
ce3ed50d JS	5	</HEAD>
ce3ed50d JS	6
4e4dc03d	7	<BODY BGCOLOR=#FFFFFF TEXT=#000000 VLINK="#00376A" LINK="#00529C" ALINK="#313063">
ce3ed50d JS	8
	9	<font face="Arial, Lucida Sans, Helvetica">
	10
4e4dc03d	11	<table width=100% border=0 cellpadding=3 cellspacing=0>
ce3ed50d	12	<tr>
4e4dc03d JS	13	<td bgcolor="#004080" align=left height=24 background="images/bluetitlegradient.gif">
4e4dc03d JS	14	<font size=+1 face="Arial, Lucida Sans, Helvetica" color="#FFFFFF">
c140b7e7	15	<b>wxWidgets 2 for GTK FAQ</b>
ce3ed50d JS	16	</font>
	17	</td>
	18	</tr>
	19	</table>
	20
	21	<P>
	22
5147354c	23	See also <a href="faq.htm">top-level FAQ page</a>
d61c1a6f	24	and <a href="faqunx.htm">Unix FAQ page</a>.
ce3ed50d	25	<hr>
8b283bb8	26	<h3>List of questions in this category</h3>
4f3b37fd JS	27
4f3b37fd JS	28	<ul>
c140b7e7 JS	29	<li><a href="#wxgtk">What is wxWidgets 2 for GTK+?</a></li>
c140b7e7 JS	30	<li><a href="#locale">Why doesn't reading floating point numbers work when using wxWidgets?</a></li>
8b283bb8 JS	31	<li><a href="#gnome">Does wxGTK have GNOME support?</a></li>
8b283bb8 JS	32	<li><a href="#redhat">Warning about GTK libraries supplied with RedHat</a></li>
4f3b37fd	33	<li><a href="#bincompat">What range of Intel Linux platforms will a given application binary be usable on?</a></li>
2b5f62a0	34	<li><a href="#static">Can I statically link the GTK+ library?</a></li>
b1c1e25b JS	35	<li><a href="#charinframe">Why does my simple program using <tt>EVT_CHAR</tt> not work?</a></li>
b1c1e25b JS	36	<li><a href="#debugging">How do I trace the cause of an X11 error such as BadMatch?</a></li>
4f3b37fd	37	</ul>
53e112a0	38
8b283bb8	39	<hr>
ce3ed50d	40
c140b7e7	41	<h3><a name="wxgtk">What is wxWidgets 2 for GTK?</a></h3>
4f3b37fd	42
c140b7e7 JS	43	wxWidgets 2 for GTK is a port of wxWidgets to the <a href="http://www.gimp.org/gtk" target=_top>GTK+ toolkit</a>,
c140b7e7 JS	44	which is freely available for most flavours of Unix with X. wxWidgets 2 for GTK is
ce3ed50d JS	45	often abbreviated to wxGTK. wxGTK has a separate home page <a href="http://www.freiburg.linux.de/~wxxt" target=_top>here</a>.
	46	<P>
	47
c140b7e7	48	<h3><a name="locale">Why doesn't reading floating point numbers work when using wxWidgets?</a></h3>
4f3b37fd JS	49
4f3b37fd JS	50	If your program reads the floating point numbers in the format <tt>123.45</tt>
966a4a52	51	from a file, it may suddenly start returning just <tt>123</tt> instead of the
4f3b37fd JS	52	correct value on some systems -- which is all the more mysterious as the same
	53	code in a standalone program works just fine.
	54
	55	<p>
	56	The explanation is that GTK+ changes the current locale on program startup. If
	57	the decimal point character in the current locale is not the period (for
	58	example, it is comma in the French locale), all the standard C functions won't
	59	recognize the numbers such as above as floating point ones any more.
	60
	61	<p>
	62	The solution is to either use your own function for reading the floating point
	63	numbers (probably the best one) or to call <tt>setlocale(LC_NUMERIC, "C")</tt>
	64	before reading from file and restore the old locale back afterwards if needed.
	65
8b283bb8	66	<h3><a name="gnome">Does wxGTK have GNOME support?</a></h3>
ce3ed50d JS	67
ce3ed50d JS	68	Currently wxGTK does not have any features that would involve dependence on any desktop
8b283bb8	69	environment's libraries, so it can work on GNOME, KDE and with other window managers
ce3ed50d JS	70	without installation hassles. Some GNOME and KDE integration features are file based, and
	71	so may be added without dependence on libraries. Other features may be supported in the
	72	future, probably as a separate library.
	73	<P>
	74
2b5f62a0	75	<h3><a name="redhat">Warning about GTK+ libraries supplied with RedHat</a></h3>
8b283bb8	76
2b5f62a0	77	It seems that some versions of RedHat include a badly patched version of GTK+ (not wxGTK)
c140b7e7	78	which causes some trouble with wxWidgets' socket code. Common symptoms are that when
8b283bb8 JS	79	a client tries to establish a connection to an existing server which refuses the request,
	80	the client will get notified twice, first getting a LOST event and then a CONNECT event.
	81	This problem can be solved by updating GTK with an official distribution of the library.
	82	<P>
	83
53e112a0 JS	84	<h3><a name="bincompat">What range of Intel Linux platforms will a given application binary be usable on?</h3>
	85
	86	Robert Roebling replies:<P>
	87
5147354c	88	"The important thing is the libc version that your app
53e112a0 JS	89	is linked against. The most recent version is 2.2.5
	90	and programs linked against it will not run with version
	91	2.1.X so that you will fare best if you compile your app
	92	on a 2.1.X system. It will then run on practically all
	93	Linux distros (if you link you app statically against
5147354c	94	the image libraries and std C++ lib)."
2b5f62a0 VZ	95	<P>
	96
	97	<h3><a name="#static">Can I statically link the GTK+ library?</a></h3>
	98
	99	No, this is not possible. It leads to crashes in GTK+.
	100	<P>
	101
	102	<h3><a name="#charinframe">Why does my simple program using
b1c1e25b	103	<tt>EVT_CHAR</tt> not work?</a></h3>
2b5f62a0 VZ	104
	105	In wxGTK, the frames never get focus and so can never receive <tt>CHAR</tt>
	106	nor <tt>KEY</tt> events so an <tt>EVT_CHAR</tt> handler for a frame will be
	107	never called. To receive these events, you should create a <tt>wxPanel</tt>
	108	inside the frame and register the key event handlers for the panel, not the
	109	frame.
	110
	111	<p>
ce3ed50d	112
b1c1e25b JS	113	<h3><a name="#debugging">How do I trace the cause of an X11 error such as BadMatch?</h3>
	114
	115	When a fatal X11 error occurs, the application quits with no stack trace.
	116	To find out where the problem is, put a breakpoint on g_log (<tt>b g_log</tt>
	117	in gdb).
	118
	119	<p>
	120
ce3ed50d JS	121	</font>
	122
	123	</BODY>
	124
	125	</HTML>