Huh? CVS removed PlugIn.c and .h (not completely without reason, BTW)...

So I added it again.

h/PlugIn

+/* Copyright 1997 Acorn Computers Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/***************************************************/
+/* File   : PlugIn.h                               */
+/*                                                 */
+/* Purpose: Supporting the generic RISC OS browser */
+/*          Plug-In interface.                     */
+/*                                                 */
+/* Author : A.D.Hodgkinson                         */
+/*                                                 */
+/* History: 28-Sep-97: Created.                    */
+/***************************************************/
+
+/* Message definitions - needs string_value to be known, */
+/* found in MiscDefs.h.                                  */
+
+#define MPlugIn_Open_OpenAsHelperNotPlugin       (1<<0);
+
+#define Message_PlugIn_Open    0x4d540
+
+typedef struct MPlugIn_Open
+{
+  unsigned int flags;
+  unsigned int reserved;
+
+  int          browser_instance_handle;
+  int          parent_window_handle;
+
+  BBox         parent_area;
+
+  int          file_type;
+  string_value file_name;
+}
+MPlugIn_Open;
+
+#define Message_PlugIn_Opening 0x4d541
+
+#define MPlugIn_Opening_CanAcceptInputFocus      (1u<<0)
+#define MPlugIn_Opening_WantsCodeResourceFetched (1u<<1)
+#define MPlugIn_Opening_WillDeleteParamsItself   (1u<<2)
+
+typedef struct MPlugIn_Opening
+{
+  unsigned int flags;
+
+  int          plugin_instance_handle;
+  int          browser_instance_handle;
+}
+MPlugIn_Opening;
+
+#define Message_PlugIn_Close   0x4d542
+
+#define MPlugIn_Close_WouldLikePlugInToExit      (1u<<0)
+
+typedef struct MPlugIn_Close
+{
+  unsigned int flags;
+
+  int          plugin_instance_handle;
+  int          browser_instance_handle;
+}
+MPlugIn_Close;
+
+#define Message_PlugIn_Closed  0x4d543
+
+typedef struct MPlugIn_Closed
+{
+  unsigned int flags;
+
+  int          plugin_instance_handle;
+  int          browser_instance_handle;
+
+  int          errnum;
+  char         errmess[sizeof(WimpMessage) - 36];
+}
+MPlugIn_Closed;
+
+#define Message_PlugIn_Reshape 0x4d544
+
+typedef struct MPlugIn_Reshape
+{
+  unsigned int flags;
+
+  int          plugin_instance_handle;
+  int          browser_instance_handle;
+
+  int          parent_window_handle;
+  BBox         parent_area;
+}
+MPlugIn_Reshape;
+
+/* Other definitions */
+
+#define PlugIn_ParamType_Terminator     0
+#define PlugIn_ParamType_DataFromPARAM  1
+#define PlugIn_ParamType_URLFromPARAM   2
+#define PlugIn_ParamType_ObjectRefPARAM 3
+#define PlugIn_ParamType_BrowserSpecial 4
+#define PlugIn_ParamType_DataFromOBJECT 5
+#define PlugIn_ParamType_URLFromOBJECT  6
+#define PlugIn_ParamType_DataFromAPPLET 5
+#define PlugIn_ParamType_URLFromAPPLET  6
+
+/* Function prototypes */
+
+const char      * plugin_return_string                (WimpMessage * m, string_value * sv);
+_kernel_oserror * plugin_write_params                 (browser_data * b, HStream * t, char * buffer, int buffer_size);
+
+_kernel_oserror * plugin_broadcast_plugin_open        (browser_data * b, HStream * t, BBox * position);
+_kernel_oserror * plugin_plugin_open_bounced          (WimpMessage * m);
+_kernel_oserror * plugin_got_plugin_opening           (WimpMessage * m);
+_kernel_oserror * plugin_send_plugin_close            (browser_data * b, unsigned int instance, unsigned int task);
+_kernel_oserror * plugin_send_original_plugin_reshape (browser_data * b, unsigned int instance, unsigned int task, BBox * position);