[Window] Allow active window to be sorted on top.

fixes: #2048

doc/rofi.1.markdown

@@ -683,6 +683,19 @@ configuration {
 
 or pass `-window-hide-active-window true` on command line.
 
+You can sort the currently active window to the top of the list with the
+'sort-active-window-first' setting:
+
+```css
+configuration {
+  window {
+      sort-active-window-first: true;
+  }
+}
+```
+
+or pass `-sort-active-window-first true` on command line.
+
 You can prefer the icon theme above the window set icon with the
 'prefer-icon-theme' setting:
 

source/modes/window.c

@@ -26,6 +26,8 @@
  */
 
 /** The log domain of this dialog. */
+#include <X11/X.h>
+#include <xcb/xproto.h>
 #define G_LOG_DOMAIN "Modes.Window"
 
 #include "config.h"
@@ -696,6 +698,25 @@ static void _window_mode_load_data(Mode *sw, unsigned int cd) {
   }
   xcb_ewmh_get_windows_reply_wipe(&clients);
 }
+
+static gint _window_mode_sort(gconstpointer a, gconstpointer b, gpointer data) {
+  WindowModePrivateData *pd = (WindowModePrivateData *)data;
+  gint wa = *(const int *)a;
+  gint wb = *(const int *)b;
+  const client *ca = window_client(pd, wa);
+  const client *cb = window_client(pd, wb);
+  if (ca == NULL || cb == NULL) {
+    return 0;
+  }
+  if (ca->active) {
+    return -1;
+  }
+  if (cb->active) {
+    return 1;
+  }
+
+  return 0;
+}
 static int window_mode_init(Mode *sw) {
   if (mode_get_private_data(sw) == NULL) {
 
@@ -717,6 +738,13 @@ static int window_mode_init(Mode *sw) {
     if (!window_matching_fields_parsed) {
       window_mode_parse_fields();
     }
+    // Sort active window first.
+    p = rofi_theme_find_property(wid, P_BOOLEAN, "sort-active-window-first",
+                                 FALSE);
+    if (p && p->type == P_BOOLEAN && p->value.b == TRUE) {
+      g_qsort_with_data(pd->ids->array, pd->ids->len, sizeof(xcb_window_t),
+                        _window_mode_sort, pd);
+    }
   }
   return TRUE;
 }
@@ -736,6 +764,13 @@ static int window_mode_init_cd(Mode *sw) {
     if (!window_matching_fields_parsed) {
       window_mode_parse_fields();
     }
+    // Sort active window first.
+    p = rofi_theme_find_property(wid, P_BOOLEAN, "sort-active-window-first",
+                                 FALSE);
+    if (p && p->type == P_BOOLEAN && p->value.b == TRUE) {
+      g_qsort_with_data(pd->ids->array, pd->ids->len, sizeof(xcb_window_t),
+                        _window_mode_sort, pd);
+    }
   }
   return TRUE;
 }