Drag and Drop: Increased payload type string to 12 characters instead of 8.(#143)

imgui.cpp

@@ -11397,7 +11397,7 @@ bool ImGui::SetDragDropPayload(const char* type, const void* data, size_t data_s
         cond = ImGuiCond_Always;
 
     IM_ASSERT(type != NULL);
-    IM_ASSERT(strlen(type) < IM_ARRAYSIZE(payload.DataType));       // Payload type can be at most 8 characters longs
+    IM_ASSERT(strlen(type) < IM_ARRAYSIZE(payload.DataType) && "Payload type can be at most 12 characters long");
     IM_ASSERT((data != NULL && data_size > 0) || (data == NULL && data_size == 0));
     IM_ASSERT(cond == ImGuiCond_Always || cond == ImGuiCond_Once);
     IM_ASSERT(payload.SourceId != 0);                               // Not called between BeginDragDropSource() and EndDragDropSource()

imgui.h

@@ -429,7 +429,7 @@ namespace ImGui
     // Drag and Drop
     // [BETA API] Missing Demo code. API may evolve.
     IMGUI_API bool          BeginDragDropSource(ImGuiDragDropFlags flags = 0, int mouse_button = 0);                // call when the current item is active. If this return true, you can call SetDragDropPayload() + EndDragDropSource()
-    IMGUI_API bool          SetDragDropPayload(const char* type, const void* data, size_t size, ImGuiCond cond = 0);// type is a user defined string of maximum 8 characters. Strings starting with '_' are reserved for dear imgui internal types. Data is copied and held by imgui.
+    IMGUI_API bool          SetDragDropPayload(const char* type, const void* data, size_t size, ImGuiCond cond = 0);// type is a user defined string of maximum 12 characters. Strings starting with '_' are reserved for dear imgui internal types. Data is copied and held by imgui.
     IMGUI_API void          EndDragDropSource();                                                                    // only call EndDragDropSource() if BeginDragDropSource() returns true!
     IMGUI_API bool          BeginDragDropTarget();                                                                  // call after submitting an item that may receive an item. If this returns true, you can call AcceptDragDropPayload() + EndDragDropTarget()
     IMGUI_API const ImGuiPayload* AcceptDragDropPayload(const char* type, ImGuiDragDropFlags flags = 0);            // accept contents of a given type. If ImGuiDragDropFlags_AcceptBeforeDelivery is set you can peek into the payload before the mouse button is released.
@@ -1239,7 +1239,7 @@ struct ImGuiPayload
     ImGuiID         SourceId;           // Source item id
     ImGuiID         SourceParentId;     // Source parent id (if available)
     int             DataFrameCount;     // Data timestamp
-    char            DataType[8 + 1];    // Data type tag (short user-supplied string)
+    char            DataType[12 + 1];   // Data type tag (short user-supplied string, 12 characters max)
     bool            Preview;            // Set when AcceptDragDropPayload() was called and mouse has been hovering the target item (nb: handle overlapping drag targets)
     bool            Delivery;           // Set when AcceptDragDropPayload() was called and mouse button is released over the target item.