ssd: make sizes of invisible SSD extents configurable

docs/labwc-config.5.scd

@@ -583,6 +583,13 @@ extending outward from the snapped edge.
 	horizontally and vertically rather than one or the other. Default is
 	half the titlebar height.
 
+*<resize><minimumArea>*
+	Treat borders of server-side decorations as if they were at least the
+	indicated thickness, regardless of their visual size. Borders visually
+	narrower than the minimum effective thickness will be augmented with
+	invisible zones just beyond the window that serve as click targets for
+	mouse actions. Default is 8.
+
 ## KEYBOARD
 
 *<keyboard><numlock>* [on|off]

docs/rc.xml.all

@@ -132,6 +132,8 @@
     <!-- Let client redraw its contents while resizing -->
     <drawContents>yes</drawContents>
     <cornerRange>8</cornerRange>
+    <!-- Borders are effectively 8 pixels wide regardless of visual appearance -->
+    <minimumArea>8</minimumArea>
   </resize>
 
   <focus>

include/config/rcxml.h

@@ -152,6 +152,7 @@ struct rcxml {
 	enum resize_indicator_mode resize_indicator;
 	bool resize_draw_contents;
 	int resize_corner_range;
+	int resize_minimum_area;
 
 	struct {
 		int popuptime;

include/ssd.h

@@ -7,8 +7,6 @@
 
 struct wlr_cursor;
 
-#define SSD_EXTENDED_AREA 8
-
 /*
  * Shadows should start at a point inset from the actual window border, see
  * discussion on https://github.com/labwc/labwc/pull/1648.  This constant

src/config/rcxml.c

@@ -1225,6 +1225,8 @@ entry(xmlNode *node, char *nodename, char *content, struct parser_state *state)
 		set_bool(content, &rc.resize_draw_contents);
 	} else if (!strcasecmp(nodename, "cornerRange.resize")) {
 		rc.resize_corner_range = atoi(content);
+	} else if (!strcasecmp(nodename, "minimumArea.resize")) {
+		rc.resize_minimum_area = MAX(0, atoi(content));
 	} else if (!strcasecmp(nodename, "mouseEmulation.tablet")) {
 		set_bool(content, &rc.tablet.force_mouse_emulation);
 	} else if (!strcasecmp(nodename, "mapToOutput.tablet")) {
@@ -1501,6 +1503,7 @@ rcxml_init(void)
 	rc.resize_indicator = LAB_RESIZE_INDICATOR_NEVER;
 	rc.resize_draw_contents = true;
 	rc.resize_corner_range = -1;
+	rc.resize_minimum_area = 8;
 
 	rc.workspace_config.popuptime = INT_MIN;
 	rc.workspace_config.min_nr_workspaces = 1;

src/ssd/ssd-extents.c

@@ -4,6 +4,7 @@
 #include <pixman.h>
 #include "common/mem.h"
 #include "common/scene-helpers.h"
+#include "config/rcxml.h"
 #include "labwc.h"
 #include "ssd-internal.h"
 #include "theme.h"
@@ -25,7 +26,8 @@ ssd_extents_create(struct ssd *ssd)
 	struct view *view = ssd->view;
 	struct theme *theme = view->server->theme;
 	struct wl_list *part_list = &ssd->extents.parts;
-	int extended_area = SSD_EXTENDED_AREA;
+
+	int border_width = MAX(0, MAX(rc.resize_minimum_area, theme->border_width));
 
 	ssd->extents.tree = wlr_scene_tree_create(ssd->tree);
 	struct wlr_scene_tree *parent = ssd->extents.tree;
@@ -34,8 +36,7 @@ ssd_extents_create(struct ssd *ssd)
 	}
 	wl_list_init(&ssd->extents.parts);
 	wlr_scene_node_set_position(&parent->node,
-		-(theme->border_width + extended_area),
+		-border_width, -(ssd->titlebar.height + border_width));
-		-(ssd->titlebar.height + theme->border_width + extended_area));
 
 	add_extent(part_list, LAB_SSD_PART_TOP, parent);
 	add_extent(part_list, LAB_SSD_PART_LEFT, parent);
@@ -68,7 +69,8 @@ ssd_extents_update(struct ssd *ssd)
 	int height = view_effective_height(view, /* use_pending */ false);
 	int full_height = height + theme->border_width * 2 + ssd->titlebar.height;
 	int full_width = width + 2 * theme->border_width;
-	int extended_area = SSD_EXTENDED_AREA;
+	int border_width = MAX(rc.resize_minimum_area, theme->border_width);
+	int extended_area = MAX(0, rc.resize_minimum_area - theme->border_width);
 
 	struct wlr_box part_box;
 	struct wlr_box result_box;
@@ -78,8 +80,7 @@ ssd_extents_update(struct ssd *ssd)
 
 	/* Make sure we update the y offset based on titlebar shown / hidden */
 	wlr_scene_node_set_position(&ssd->extents.tree->node,
-		-(theme->border_width + extended_area),
+		-border_width, -(ssd->titlebar.height + border_width));
-		-(ssd->titlebar.height + theme->border_width + extended_area));
 
 	/*
 	 * Convert all output usable areas that the