wxWidgets for GTK FAQ

See also top-level FAQ page and Unix FAQ page.

### List of questions in this category

- What is wxWidgets for GTK+?
- Why doesn't reading floating point numbers work when using wxWidgets?
- Does wxGTK have GNOME support?
- Warning about GTK libraries supplied with RedHat
- What range of Intel Linux platforms will a given application binary be usable on?
- Can I statically link the GTK+ library?
- Why does my simple program using `EVT_CHAR` not work?
- How do I trace the cause of an X11 error such as BadMatch?

### What is wxWidgets for GTK?

wxWidgets for GTK is a port of wxWidgets to the GTK+ toolkit, which is freely available for most flavours of Unix with X. wxWidgets for GTK is often abbreviated to wxGTK. wxGTK has a separate home page here.

### Why doesn't reading floating point numbers work when using wxWidgets?

If your program reads the floating point numbers in the format `123.45` from a file, it may suddenly start returning just `123` 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.

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't recognize the numbers such as above as floating point ones any more.

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

### Does wxGTK have GNOME support?

Currently wxGTK does not have any features that would involve dependence on any desktop environment'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.

### Warning about GTK+ libraries supplied with RedHat

It seems that some versions of RedHat include a badly patched version of GTK+ (not wxGTK) which causes some trouble with wxWidgets' 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.

### What range of Intel Linux platforms will a given application binary be usable on?

Robert Roebling replies:

"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)."

### Can I statically link the GTK+ library?

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

### Why does my simple program using `EVT_CHAR` not work?

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

### How do I trace the cause of an X11 error such as BadMatch?

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 (`b g_log` in gdb).