Added group scrollbar scroll wheel and shortcuts

It is now possible to use mouse scrolling as well as shortcuts for
windows as well as groups. But there is still some unwanted behavior
if you scroll the window and while scrolling hover over a group then
the group will be scrolled and not the window. I will look into fixing
it.

nuklear.h

@@ -2269,6 +2269,7 @@ struct nk_panel {
     float footer_h;
     float header_h;
     float border;
+	unsigned int has_scrolling;
     struct nk_rect clip;
     struct nk_menu_state menu;
     struct nk_row_layout row;
@@ -2359,6 +2360,7 @@ struct nk_window {
     struct nk_property_state property;
     struct nk_popup_state popup;
     struct nk_edit_state edit;
+	unsigned int scrolled;
 
     struct nk_table *tables;
     unsigned short table_count;
@@ -12420,33 +12422,33 @@ nk_scrollbar_behavior(nk_flags *state, struct nk_input *in,
             cursor_x = scroll->x + ((scroll_offset/target) * scroll->w);
             in->mouse.buttons[NK_BUTTON_LEFT].clicked_pos.x = cursor_x + cursor->w/2.0f;
         }
-    } else if (has_scrolling && ((in->mouse.scroll_delta<0) ||
-            (in->mouse.scroll_delta>0))) {
-        /* update cursor by mouse scrolling */
-        scroll_offset = scroll_offset + scroll_step * (-in->mouse.scroll_delta);
-        if (o == NK_VERTICAL)
-            scroll_offset = NK_CLAMP(0, scroll_offset, target - scroll->h);
-        else scroll_offset = NK_CLAMP(0, scroll_offset, target - scroll->w);
-    } else if ((nk_input_is_key_pressed(in, NK_KEY_SCROLL_UP) && o == NK_VERTICAL)||
+    } else if ((nk_input_is_key_pressed(in, NK_KEY_SCROLL_UP) && o == NK_VERTICAL && has_scrolling)||
             nk_button_behavior(&ws, *empty0, in, NK_BUTTON_DEFAULT)) {
         /* scroll page up by click on empty space or shortcut */
         if (o == NK_VERTICAL)
             scroll_offset = NK_MAX(0, scroll_offset - scroll->h);
         else scroll_offset = NK_MAX(0, scroll_offset - scroll->w);
-    } else if ((nk_input_is_key_pressed(in, NK_KEY_SCROLL_DOWN) && o == NK_VERTICAL)||
-            nk_button_behavior(&ws, *empty1, in, NK_BUTTON_DEFAULT)){
+    } else if ((nk_input_is_key_pressed(in, NK_KEY_SCROLL_DOWN) && o == NK_VERTICAL && has_scrolling) ||
+        nk_button_behavior(&ws, *empty1, in, NK_BUTTON_DEFAULT)) {
         /* scroll page down by click on empty space or shortcut */
         if (o == NK_VERTICAL)
             scroll_offset = NK_MIN(scroll_offset + scroll->h, target - scroll->h);
         else scroll_offset = NK_MIN(scroll_offset + scroll->w, target - scroll->w);
-    } else if (nk_input_is_key_pressed(in, NK_KEY_SCROLL_START)) {
-        /* update cursor to the beginning  */
-        if (o == NK_VERTICAL) scroll_offset = 0;
-    } else if (nk_input_is_key_pressed(in, NK_KEY_SCROLL_END)) {
-        /* update cursor to the end */
-        if (o == NK_VERTICAL) scroll_offset = target - scroll->h;
+    } else if (has_scrolling) {
+        if ((in->mouse.scroll_delta<0 || (in->mouse.scroll_delta>0))) {
+            /* update cursor by mouse scrolling */
+            scroll_offset = scroll_offset + scroll_step * (-in->mouse.scroll_delta);
+            if (o == NK_VERTICAL)
+                scroll_offset = NK_CLAMP(0, scroll_offset, target - scroll->h);
+            else scroll_offset = NK_CLAMP(0, scroll_offset, target - scroll->w);
+        } else if (nk_input_is_key_pressed(in, NK_KEY_SCROLL_START)) {
+            /* update cursor to the beginning  */
+            if (o == NK_VERTICAL) scroll_offset = 0;
+        } else if (nk_input_is_key_pressed(in, NK_KEY_SCROLL_END)) {
+            /* update cursor to the end */
+            if (o == NK_VERTICAL) scroll_offset = target - scroll->h;
+        }
     }
-
     if (*state & NK_WIDGET_STATE_HOVER && !nk_input_is_mouse_prev_hovering_rect(in, *scroll))
         *state |= NK_WIDGET_STATE_ENTERED;
     else if (nk_input_is_mouse_prev_hovering_rect(in, *scroll))
@@ -14822,6 +14824,7 @@ nk_create_table(struct nk_context *ctx)
 {
     struct nk_page_element *elem = nk_create_page_element(ctx);
     if (!elem) return 0;
+    nk_zero_struct(*elem);
     return &elem->data.tbl;
 }
 
@@ -14841,7 +14844,7 @@ nk_push_table(struct nk_window *win, struct nk_table *tbl)
         tbl->next = 0;
         tbl->prev = 0;
         win->table_count = 1;
-        win->table_size = 1;
+        win->table_size = 0;
         return;
     }
     win->tables->prev = tbl;
@@ -14869,8 +14872,13 @@ NK_INTERN nk_uint*
 nk_add_value(struct nk_context *ctx, struct nk_window *win,
             nk_hash name, nk_uint value)
 {
-    if (!win->tables || win->table_size == NK_VALUE_PAGE_CAPACITY) {
+    NK_ASSERT(ctx);
+    NK_ASSERT(win);
+    if (!win || !ctx) return 0;
+    if (!win->tables || win->table_size >= NK_VALUE_PAGE_CAPACITY) {
         struct nk_table *tbl = nk_create_table(ctx);
+        NK_ASSERT(tbl);
+        if (!tbl) return 0;
         nk_push_table(win, tbl);
     }
     win->tables->seq = win->seq;
@@ -15612,6 +15620,7 @@ nk_panel_begin(struct nk_context *ctx, const char *title)
     layout->row.item_width = 0;
     layout->row.tree_depth = 0;
     layout->flags = win->flags;
+    layout->has_scrolling = nk_true;
     out = &win->buffer;
 
     /* calculate window header */
@@ -15911,13 +15920,41 @@ nk_panel_end(struct nk_context *ctx)
             scroll_step = bounds.h * 0.10f;
             scroll_inc = bounds.h * 0.01f;
             scroll_target = (float)(int)(layout->at_y - bounds.y);
-            if (!(window->flags & NK_WINDOW_SUB)) {
-                scroll_has_scrolling = (window == ctx->active);
-            } else scroll_has_scrolling = 0;
+
+            /* scrolling by mouse wheel */
+            if ((window->flags & NK_WINDOW_SUB) && (window->flags &NK_WINDOW_GROUP)) {
+                /* group scrollbar wheel scrolling */
+                struct nk_panel *root;
+                root = window->layout;
+                while (root->parent)
+                    root = root->parent;
+
+                /* only allow scrolling if parent window is active */
+                scroll_has_scrolling = 0;
+                if (!(root->flags & NK_WINDOW_ROM)) {
+                    /* and groups is being hovered and inside clip rect*/
+                    if (nk_input_is_mouse_hovering_rect(in, layout->bounds) &&
+                        NK_INTERSECT(layout->bounds.x, layout->bounds.y, layout->bounds.w, layout->bounds.h,
+                            root->clip.x, root->clip.y, root->clip.w, root->clip.h))
+                    {
+                        scroll_has_scrolling = nk_true;
+                        root->has_scrolling = nk_false;
+                    }
+                }
+            } else if (!(window->flags & NK_WINDOW_SUB)) {
+                /* window scrollbar wheel scrolling */
+                scroll_has_scrolling = (window == ctx->active) && layout->has_scrolling;
+                if (in->mouse.scroll_delta && scroll_has_scrolling)
+                    window->scrolled = nk_true;
+                else window->scrolled = nk_false;
+            } else scroll_has_scrolling = nk_false;
+
             scroll_offset = nk_do_scrollbarv(&state, out, bounds, scroll_has_scrolling,
                     scroll_offset, scroll_target, scroll_step, scroll_inc,
                     &ctx->style.scrollv, in, &style->font);
             layout->offset->y = (unsigned short)scroll_offset;
+            if (scroll_has_scrolling)
+                in->mouse.scroll_delta = 0;
         }
         {
             /* horizontal scrollbar */
@@ -18807,7 +18844,8 @@ nk_contextual_begin(struct nk_context *ctx, struct nk_panel *layout,
     if (ret) win->popup.type = NK_WINDOW_CONTEXTUAL;
     else {
         win->popup.active_con = 0;
-        win->popup.win->flags = 0;
+		if (win->popup.win)
+			win->popup.win->flags = 0;
     }
     return ret;
 }