Index: trunk/src_plugins/dialogs/dlg_pref.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref.c	(revision 35845)
@@ -505,8 +505,17 @@
 
 void pcb_dlg_pref_uninit(void)
 {
+	int t;
+
 	rnd_event_unbind_allcookie(pref_cookie);
 	rnd_conf_hid_unreg(pref_cookie);
+
+	for(t = 0; t < pref_ctx.tabs; t++) {
+		if (pref_ctx.tab[t].hooks->flags & Rnd_PREFTAB_AUTO_FREE_DATA) {
+			free(pref_ctx.tab[t].tabdata);
+			pref_ctx.tab[t].tabdata = NULL;
+		}
+	}
 }
 
 const char pcb_acts_Preferences[] = "Preferences([tabname])\n";
Index: trunk/src_plugins/dialogs/dlg_pref.h
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref.h	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref.h	(revision 35845)
@@ -24,7 +24,8 @@
 };
 
 typedef enum Rnd_pref_tab_flag_e { /* bitfield */
-	Rnd_PREFTAB_NEEDS_ROLE = 1
+	Rnd_PREFTAB_NEEDS_ROLE = 1,
+	Rnd_PREFTAB_AUTO_FREE_DATA = 2       /* free tab data when plugin is unloaded */
 } Rnd_pref_tab_flag_t;
 
 typedef struct Rnd_pref_tab_hook_s Rnd_pref_tab_hook_t;
Index: trunk/src_plugins/dialogs/dlg_pref_board.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_board.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_board.c	(revision 35845)
@@ -100,7 +100,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_board = {
-	"Board meta", 0,
+	"Board meta", Rnd_PREFTAB_AUTO_FREE_DATA,
 	NULL, NULL,
 	pcb_dlg_pref_board_create,
 	pref_board_brd2dlg, pref_board_brd2dlg  /* board change, meta change */
Index: trunk/src_plugins/dialogs/dlg_pref_color.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_color.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_color.c	(revision 35845)
@@ -169,7 +169,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_color = {
-	"Colors", Rnd_PREFTAB_NEEDS_ROLE,
+	"Colors", Rnd_PREFTAB_AUTO_FREE_DATA | Rnd_PREFTAB_NEEDS_ROLE,
 	pcb_dlg_pref_color_open, pcb_dlg_pref_color_close,
 	pcb_dlg_pref_color_create,
 	pref_color_brd2dlg, pref_color_brd2dlg  /* board change, meta change */
Index: trunk/src_plugins/dialogs/dlg_pref_general.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_general.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_general.c	(revision 35845)
@@ -93,7 +93,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_general = {
-	"General", Rnd_PREFTAB_NEEDS_ROLE,
+	"General", Rnd_PREFTAB_AUTO_FREE_DATA | Rnd_PREFTAB_NEEDS_ROLE,
 	NULL, pcb_dlg_pref_general_close,
 	pcb_dlg_pref_general_create,
 	NULL, NULL
Index: trunk/src_plugins/dialogs/dlg_pref_layer.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_layer.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_layer.c	(revision 35845)
@@ -61,7 +61,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_layer = {
-	"Layers", 0,
+	"Layers", Rnd_PREFTAB_AUTO_FREE_DATA,
 	NULL, NULL,
 	pcb_dlg_pref_layer_create,
 	NULL, NULL
Index: trunk/src_plugins/dialogs/dlg_pref_lib.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_lib.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_lib.c	(revision 35845)
@@ -468,7 +468,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_lib = {
-	"Library", Rnd_PREFTAB_NEEDS_ROLE,
+	"Library", Rnd_PREFTAB_AUTO_FREE_DATA | Rnd_PREFTAB_NEEDS_ROLE,
 	pcb_dlg_pref_lib_open, pcb_dlg_pref_lib_close,
 	pcb_dlg_pref_lib_create,
 	NULL, NULL
Index: trunk/src_plugins/dialogs/dlg_pref_sizes.c
===================================================================
--- trunk/src_plugins/dialogs/dlg_pref_sizes.c	(revision 35844)
+++ trunk/src_plugins/dialogs/dlg_pref_sizes.c	(revision 35845)
@@ -158,7 +158,7 @@
 }
 
 static const Rnd_pref_tab_hook_t pref_sizes = {
-	"Sizes & DRC", Rnd_PREFTAB_NEEDS_ROLE,
+	"Sizes & DRC", Rnd_PREFTAB_AUTO_FREE_DATA | Rnd_PREFTAB_NEEDS_ROLE,
 	NULL, pcb_dlg_pref_sizes_close,
 	pcb_dlg_pref_sizes_create,
 	pref_sizes_brd2dlg, pref_sizes_brd2dlg  /* board change, meta change */