Context:

Added a system for adding a "local" context in a UI layout.
This way you can define for example within a modifier panel
all operators to get the modifier in the context.

In the layout code:

uiLayoutSetContextPointer(layout, "modifier", &ptr)
layout.set_context_pointer("modifier", md)

In the operator:

ptr = CTX_data_pointer_get(C, "modifier")
md = context.modifier

source/blender/blenkernel/BKE_context.h

@@ -72,6 +72,20 @@ typedef struct bContextDataResult bContextDataResult;
 typedef int (*bContextDataCallback)(const bContext *C,
 	const char *member, bContextDataResult *result);
 
+typedef struct bContextStoreEntry {
+	struct bContextStoreEntry *next, *prev;
+
+	char name[128];
+	PointerRNA ptr;
+} bContextStoreEntry;
+
+typedef struct bContextStore {
+	struct bContextStore *next, *prev;
+
+	ListBase entries;
+	int used;
+} bContextStore;
+
 /* Context */
 
 bContext *CTX_create(void);
@@ -79,6 +93,14 @@ void CTX_free(bContext *C);
 
 bContext *CTX_copy(const bContext *C);
 
+/* Stored Context */
+
+bContextStore *CTX_store_add(ListBase *contexts, char *name, PointerRNA *ptr);
+void CTX_store_set(bContext *C, bContextStore *store);
+bContextStore *CTX_store_copy(bContextStore *store);
+void CTX_store_free(bContextStore *store);
+void CTX_store_free_list(ListBase *contexts);
+
 /* Window Manager Context */
 
 struct wmWindowManager *CTX_wm_manager(const bContext *C);

source/blender/blenkernel/intern/context.c

@@ -38,6 +38,7 @@
 #include "RNA_access.h"
 
 #include "BLI_listbase.h"
+#include "BLI_string.h"
 
 #include "BKE_context.h"
 #include "BKE_main.h"
@@ -58,6 +59,7 @@ struct bContext {
 		struct ScrArea *area;
 		struct ARegion *region;
 		struct ARegion *menu;
+		struct bContextStore *store;
 	} wm;
 	
 	/* data context */
@@ -97,6 +99,69 @@ void CTX_free(bContext *C)
 	MEM_freeN(C);
 }
 
+/* store */
+
+bContextStore *CTX_store_add(ListBase *contexts, char *name, PointerRNA *ptr)
+{
+	bContextStoreEntry *entry;
+	bContextStore *ctx, *lastctx;
+
+	/* ensure we have a context to put the entry in, if it was already used
+	 * we have to copy the context to ensure */
+	ctx= contexts->last;
+
+	if(!ctx || ctx->used) {
+		if(ctx) {
+			lastctx= ctx;
+			ctx= MEM_dupallocN(lastctx);
+			BLI_duplicatelist(&ctx->entries, &lastctx->entries);
+		}
+		else
+			ctx= MEM_callocN(sizeof(bContextStore), "bContextStore");
+
+		BLI_addtail(contexts, ctx);
+	}
+
+	entry= MEM_callocN(sizeof(bContextStoreEntry), "bContextStoreEntry");
+	BLI_strncpy(entry->name, name, sizeof(entry->name));
+	entry->ptr= *ptr;
+
+	BLI_addtail(&ctx->entries, entry);
+
+	return ctx;
+}
+
+void CTX_store_set(bContext *C, bContextStore *store)
+{
+	C->wm.store= store;
+}
+
+bContextStore *CTX_store_copy(bContextStore *store)
+{
+	bContextStore *ctx;
+
+	ctx= MEM_dupallocN(store);
+	BLI_duplicatelist(&ctx->entries, &store->entries);
+
+	return ctx;
+}
+
+void CTX_store_free(bContextStore *store)
+{
+	BLI_freelistN(&store->entries);
+	MEM_freeN(store);
+}
+
+void CTX_store_free_list(ListBase *contexts)
+{
+	bContextStore *ctx;
+
+	while((ctx= contexts->first)) {
+		BLI_remlink(contexts, ctx);
+		CTX_store_free(ctx);
+	}
+}
+
 /* window manager context */
 
 wmWindowManager *CTX_wm_manager(const bContext *C)
@@ -225,19 +290,31 @@ static int ctx_data_get(bContext *C, const char *member, bContextDataResult *res
 
 	/* we check recursion to ensure that we do not get infinite
 	 * loops requesting data from ourselfs in a context callback */
-	if(!done && recursion < 1 && C->wm.region) {
+	if(!done && recursion < 1 && C->wm.store) {
+		bContextStoreEntry *entry;
+
 		C->data.recursion= 1;
+
+		for(entry=C->wm.store->entries.first; entry; entry=entry->next) {
+			if(strcmp(entry->name, member) == 0) {
+				result->ptr= entry->ptr;
+				done= 1;
+			}
+		}
+	}
+	if(!done && recursion < 2 && C->wm.region) {
+		C->data.recursion= 2;
 		if(C->wm.region->type && C->wm.region->type->context)
 			done= C->wm.region->type->context(C, member, result);
 	}
-	if(!done && recursion < 2 && C->wm.area) {
-		C->data.recursion= 2;
+	if(!done && recursion < 3 && C->wm.area) {
+		C->data.recursion= 3;
 		if(C->wm.area->type && C->wm.area->type->context)
 			done= C->wm.area->type->context(C, member, result);
 	}
-	if(!done && recursion < 3 && C->wm.screen) {
+	if(!done && recursion < 4 && C->wm.screen) {
 		bContextDataCallback cb= C->wm.screen->context;
-		C->data.recursion= 3;
+		C->data.recursion= 4;
 		if(cb)
 			done= cb(C, member, result);
 	}

source/blender/editors/include/UI_interface.h

@@ -541,12 +541,13 @@ uiBut *uiDefMenuTogR(uiBlock *block, struct PointerRNA *ptr, char *propname, cha
 uiLayout *uiBlockLayout(uiBlock *block, int dir, int type, int x, int y, int size, int em, struct uiStyle *style);
 void uiBlockSetCurLayout(uiBlock *block, uiLayout *layout);
 void uiBlockLayoutResolve(const struct bContext *C, uiBlock *block, int *x, int *y);
-float uiBlockAspect(uiBlock *block); /* temporary */
 
 void uiLayoutContext(uiLayout *layout, int opcontext);
 void uiLayoutFunc(uiLayout *layout, uiMenuHandleFunc handlefunc, void *argv);
 uiBlock *uiLayoutBlock(uiLayout *layout);
 
+void uiLayoutSetContextPointer(uiLayout *layout, char *name, struct PointerRNA *ptr);
+
 /* layout specifiers */
 uiLayout *uiLayoutRow(uiLayout *layout, int align);
 uiLayout *uiLayoutColumn(uiLayout *layout, int align);

source/blender/editors/interface/interface.c

@@ -1692,6 +1692,8 @@ void uiFreeBlock(const bContext *C, uiBlock *block)
 		ui_free_but(C, but);
 	}
 
+	CTX_store_free_list(&block->contexts);
+
 	BLI_freelistN(&block->saferct);
 	
 	MEM_freeN(block);

source/blender/editors/interface/interface_api.c

@@ -175,6 +175,13 @@ void RNA_api_ui_layout(StructRNA *srna)
 
 	func= RNA_def_function(srna, "itemS", "uiItemS");
 
+	/* context */
+	func= RNA_def_function(srna, "set_context_pointer", "uiLayoutSetContextPointer");
+	parm= RNA_def_string(func, "name", "", 0, "Name", "Name of entry in the context.");
+	RNA_def_property_flag(parm, PROP_REQUIRED);
+	parm= RNA_def_pointer(func, "data", "AnyType", "", "Pointer to put in context.");
+	RNA_def_property_flag(parm, PROP_REQUIRED);
+
 	/* templates */
 	func= RNA_def_function(srna, "template_header", "uiTemplateHeader");
 	parm= RNA_def_pointer(func, "context", "Context", "", "Current context.");

source/blender/editors/interface/interface_intern.h

@@ -43,6 +43,7 @@ struct wmWindow;
 struct uiStyle;
 struct uiWidgetColors;
 struct uiLayout;
+struct bContextStore;
 
 /* ****************** general defines ************** */
 
@@ -166,6 +167,8 @@ struct uiBut {
 	uiButHandleNFunc funcN;
 	void *func_argN;
 
+	struct bContextStore *context;
+
 	void (*embossfunc)(int , int , float, float, float, float, float, int);
 	void (*sliderfunc)(int , float, float, float, float, float, float, int);
 
@@ -224,6 +227,8 @@ struct uiBlock {
 
 	ListBase layouts;
 	struct uiLayout *curlayout;
+
+	ListBase contexts;
 	
 	char name[UI_MAX_NAME_STR];
 	

source/blender/editors/interface/interface_layout.c

@@ -126,6 +126,7 @@ struct uiLayout {
 	uiItem item;
 
 	uiLayoutRoot *root;
+	bContextStore *context;
 	ListBase items;
 
 	int x, y, w, h;
@@ -1731,6 +1732,11 @@ void ui_layout_add_but(uiLayout *layout, uiBut *but)
 	bitem->item.type= ITEM_BUTTON;
 	bitem->but= but;
 	BLI_addtail(&layout->items, bitem);
+
+	if(layout->context) {
+		but->context= layout->context;
+		but->context->used= 1;
+	}
 }
 
 void uiLayoutContext(uiLayout *layout, int opcontext)
@@ -1769,8 +1775,9 @@ void uiBlockLayoutResolve(const bContext *C, uiBlock *block, int *x, int *y)
 	}
 }
 
-float uiBlockAspect(uiBlock *block)
+void uiLayoutSetContextPointer(uiLayout *layout, char *name, PointerRNA *ptr)
 {
-	return block->aspect; /* temporary */
+	uiBlock *block= layout->root->block;
+	layout->context= CTX_store_add(&block->contexts, name, ptr);
 }