Fix segfault on Linux when typing in a TexBox

See https://github.com/AvaloniaUI/Avalonia/issues/12049

src/Avalonia.X11/X11Info.cs

@@ -34,7 +34,10 @@ namespace Avalonia.X11
         public bool HasXim { get; set; }
         public bool HasXSync { get; set; }
         public IntPtr DefaultFontSet { get; set; }
-        
+
+        [DllImport("libc")]
+        private static extern void setlocale(int type, string s);
+
         public unsafe X11Info(IntPtr display, IntPtr deferredDisplay, bool useXim)
         {
             Display = display;
@@ -48,7 +51,10 @@ namespace Avalonia.X11
 
             DefaultFontSet = XCreateFontSet(Display, "-*-*-*-*-*-*-*-*-*-*-*-*-*-*",
                 out var _, out var _, IntPtr.Zero);
-            
+
+            // We have problems with text input otherwise
+            setlocale(0, "");
+
             if (useXim)
             {
                 XSetLocaleModifiers("");
@@ -59,7 +65,15 @@ namespace Avalonia.X11
 
             if (Xim == IntPtr.Zero)
             {
-                XSetLocaleModifiers("@im=none");
+                if (XSetLocaleModifiers("@im=none") == IntPtr.Zero)
+                {
+                    setlocale(0, "en_US.UTF-8");
+                    if (XSetLocaleModifiers("@im=none") == IntPtr.Zero)
+                    {
+                        setlocale(0, "C.UTF-8");
+                        XSetLocaleModifiers("@im=none");
+                    }
+                }
                 Xim = XOpenIM(display, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
             }
 

src/Avalonia.X11/X11Platform.cs

@@ -36,12 +36,11 @@ namespace Avalonia.X11
         public IntPtr OrphanedWindow { get; private set; }
         public X11Globals Globals { get; private set; }
         public ManualRawEventGrouperDispatchQueue EventGrouperDispatchQueue { get; } = new();
-        [DllImport("libc")]
-        private static extern void setlocale(int type, string s);
+
         public void Initialize(X11PlatformOptions options)
         {
             Options = options;
-            
+
             bool useXim = false;
             if (EnableIme(options))
             {
@@ -50,9 +49,6 @@ namespace Avalonia.X11
                     useXim = true;
             }
 
-            // We have problems with text input otherwise
-            setlocale(0, "");
-
             XInitThreads();
             Display = XOpenDisplay(IntPtr.Zero);
             if (Display == IntPtr.Zero)
@@ -64,7 +60,7 @@ namespace Avalonia.X11
             OrphanedWindow = XCreateSimpleWindow(Display, XDefaultRootWindow(Display), 0, 0, 1, 1, 0, IntPtr.Zero,
                 IntPtr.Zero);
             XError.Init();
-            
+
             Info = new X11Info(Display, DeferredDisplay, useXim);
             Globals = new X11Globals(this);
             //TODO: log

src/Avalonia.X11/X11Window.Ime.cs

@@ -133,14 +133,21 @@ namespace Avalonia.X11
         {
             if (ImeBuffer == IntPtr.Zero)
                 ImeBuffer = Marshal.AllocHGlobal(ImeBufferSize);
-            
-            var len = Xutf8LookupString(_xic, ref ev, ImeBuffer.ToPointer(), ImeBufferSize, 
-                out _, out var istatus);
-            var status = (XLookupStatus)istatus;
+
+            IntPtr istatus;
+            int len;
+            if(_xic != IntPtr.Zero)
+                len = Xutf8LookupString(_xic, ref ev, ImeBuffer.ToPointer(),
+                    ImeBufferSize, out _, out istatus);
+            else
+                len = XLookupString(ref ev, ImeBuffer.ToPointer(), ImeBufferSize,
+                    out _, out istatus);
 
             if (len == 0)
                 return null;
 
+            var status = (XLookupStatus)istatus;
+
             string text;
             if (status == XLookupStatus.XBufferOverflow)
                 return null;

src/Avalonia.X11/XLib.cs

@@ -468,7 +468,7 @@ namespace Avalonia.X11
         public static extern unsafe int XLookupString(ref XEvent xevent, void* buffer, int num_bytes, out IntPtr keysym, out IntPtr status);
         
         [DllImport (libX11)]
-        public static extern unsafe int Xutf8LookupString(IntPtr xic, ref XEvent xevent, void* buffer, int num_bytes, out IntPtr keysym, out UIntPtr status);
+        public static extern unsafe int Xutf8LookupString(IntPtr xic, ref XEvent xevent, void* buffer, int num_bytes, out IntPtr keysym, out IntPtr status);
         
         [DllImport (libX11)]
         public static extern unsafe int Xutf8LookupString(IntPtr xic, XEvent* xevent, void* buffer, int num_bytes, out IntPtr keysym, out IntPtr status);