Add node_collapse_policy setting

The original behavior was to always collapse (`node_collapse_policy = 0`)

README.md

@@ -44,6 +44,13 @@ plugin {
     # disable gaps when only one window is onscreen
     no_gaps_when_only = <bool>
 
+    # policy controlling what happens when a node is removed from a group,
+    # leaving only a group
+    # 0 = remove the nested group
+    # 1 = keep the nested group
+    # 2 = keep the nested group only if its parent is a tab group (default)
+    node_collapse_policy = <int>
+
     # offset from group split direction when only one window is in a group
     group_inset = <int>
 

src/Hy3Layout.cpp

@@ -193,6 +193,9 @@ void Hy3Layout::onWindowCreatedTiling(CWindow* window) {
 }
 
 void Hy3Layout::onWindowRemovedTiling(CWindow* window) {
+	static const auto* node_collapse_policy
+	    = &HyprlandAPI::getConfigValue(PHANDLE, "plugin:hy3:node_collapse_policy")->intValue;
+
 	auto* node = this->getNodeFromWindow(window);
 	Debug::log(LOG, "remove tiling %p (window %p)", node, window);
 
@@ -217,8 +220,16 @@ void Hy3Layout::onWindowRemovedTiling(CWindow* window) {
 	if (parent != nullptr) {
 		parent->recalcSizePosRecursive();
 
+		// returns if a given node is a group that can be collapsed given the current config
+		auto node_is_collapsible = [](Hy3Node* node) {
+			if (node->data.type != Hy3NodeType::Group) return false;
+			if (*node_collapse_policy == 0) return true;
+			else if (*node_collapse_policy == 1) return false;
+			return node->parent->data.as_group.layout != Hy3GroupLayout::Tabbed;
+		};
+
 		if (group.children.size() == 1
-		    && (group.ephemeral || group.children.front()->data.type == Hy3NodeType::Group))
+		    && (group.ephemeral || node_is_collapsible(group.children.front())))
 		{
 			auto* target_parent = parent;
 			while (target_parent != nullptr && Hy3Node::swallowGroups(target_parent)) {

src/main.cpp

@@ -19,6 +19,11 @@ APICALL EXPORT PLUGIN_DESCRIPTION_INFO PLUGIN_INIT(HANDLE handle) {
 	    "plugin:hy3:no_gaps_when_only",
 	    SConfigValue {.intValue = 0}
 	);
+	HyprlandAPI::addConfigValue(
+	    PHANDLE,
+	    "plugin:hy3:node_collapse_policy",
+	    SConfigValue {.intValue = 2}
+	);
 	HyprlandAPI::addConfigValue(PHANDLE, "plugin:hy3:group_inset", SConfigValue {.intValue = 10});
 	HyprlandAPI::addConfigValue(PHANDLE, "plugin:hy3:tabs:height", SConfigValue {.intValue = 15});
 	HyprlandAPI::addConfigValue(PHANDLE, "plugin:hy3:tabs:padding", SConfigValue {.intValue = 5});