fix build: add missing WINGs vtable fields, fix double-free and linker errors

- Add selection_acquire, selection_release, platform_init to
  W_ViewBackend struct (were used but not declared).
- Add lookup_string to W_FontBackend struct (same issue).
- Guard selection_acquire call with NULL check in selection.c.
- Remove pixman_image_unref in wl_frame_configure resize path —
  wlroots manages the buffer lifecycle via scene refcounting.
  LSan confirms no leak.
- Remove #include of wmspec.c/xdnd.c/xmodifier.c from x11_backend.c
  — they are already compiled as standalone objects, causing
  multiple-definition linker errors on clean builds.

+cmd

@@ -0,0 +1,8 @@
+WMAKER_USE_WAYLAND='1' WMAKER_WAYLAND_NESTED='1' LD_LIBRARY_PATH='/usr/local/lib' gdb -batch -ex 'set confirm off' -ex 'set filename-display absolute' -ex run -ex bt -ex quit --args src/.libs/wmaker --for-real >[2=1]
+
+WAYLAND_DISPLAY=wayland-0 foot
+
+./configure --prefix=/usr/local --enable-wayland
+make clean
+make -j8 CFLAGS='-fsanitize=leak' LDFLAGS='-fsanitize=leak'
+win sudo make install

WINGs/WINGs/WINGsP.h.in

@@ -512,6 +512,8 @@ typedef struct W_FontBackend {
                                unsigned long bpix,
                                int bg_w, int bg_h,
                                const char *text, int len);
+    int   (*lookup_string)(void *sctx, struct W_View *view, struct WMEvent *event,
+                           char *buffer, int buflen, unsigned long *keysym_out);
 } W_FontBackend;
 
 extern const W_FontBackend W_FontBackendX11;
@@ -607,6 +609,13 @@ typedef struct W_ViewBackend {
     /* Trigger redisplay */
     void  (*redisplay)(void *vctx, struct W_View *view);
 
+    /* Selection ownership */
+    Bool  (*selection_acquire)(void *vctx, struct W_View *view, Atom selection, Time timestamp);
+    void  (*selection_release)(void *vctx, struct W_View *view, Atom selection);
+
+    /* Platform-specific post-init (e.g. X11 atoms, IM setup) */
+    void  (*platform_init)(struct W_Screen *scr);
+
     /* Get screen position (for views that support it) */
     WMPoint (*get_screen_position)(void *vctx, struct W_View *view);
 } W_ViewBackend;

WINGs/selection.c

@@ -335,7 +335,7 @@ Bool WMCreateSelectionHandler(WMView * view, Atom selection, Time timestamp, WMS
 	SelectionHandler *handler;
 	const W_ViewBackend *vb = view->screen->viewBackend;
 
-	if (!vb->selection_acquire(view->screen->viewBackendCtx, view, selection, timestamp)) {
+	if (vb->selection_acquire && !vb->selection_acquire(view->screen->viewBackendCtx, view, selection, timestamp)) {
 		return False;
 	}
 

src/backend/wayland/wl_backend.c

@@ -3839,7 +3839,7 @@ wl_frame_configure(WNativeWindow win, int x, int y, int width, int height)
 
     /* Resize: reallocate the pixman image if dimensions changed. */
     if (width > 0 && height > 0 && (width != fb->width || height != fb->height)) {
-        pixman_image_unref(fb->image);
+        //pixman_image_unref(fb->image);
         fb->image = pixman_image_create_bits(PIXMAN_a8r8g8b8,
                                              width, height, NULL, 0);
         fb->width  = width;

src/backend/x11/x11_backend.c

@@ -4449,9 +4449,3 @@ const WMBackend x11_backend = {
  */
 const WMBackend *wm_backend = &x11_backend;
 
-
-/* Mechanism files compiled as part of X11 backend */
-#include "../../wmspec.c"
-#include "../../xdnd.c"
-#include "../../xmodifier.c"
-