additional focus management for popups

When a menupopup is opened, the active element does not change, so
their focus-ring will be hidden until the menupopup closes for it to be
less distracting.

When a panel popup is opened, the focus will be moved inside
of the panel, so we keep track of whichever element was previously
focused, and re-focus it when the panel goes away.

Minor reorganization of focus-ring mixin to use variables instead
of parameters to make hiding of focus-ring easier.

chrome/content/zotero/zoteroPane.js

@@ -37,6 +37,7 @@ var ZoteroPane = new function()
 	this._listeners = {};
 	this.__defineGetter__('loaded', function () { return _loaded; });
 	var _lastSelectedItems = [];
+	var lastFocusedElement = null;
 	
 	//Privileged methods
 	this.destroy = destroy;
@@ -434,7 +435,29 @@ var ZoteroPane = new function()
 		});
 	}
 
-	
+	function addFocusHandlers() {
+		// When a menupopup shows, hide the focus ring around the currently focused element
+		document.addEventListener("popupshowing", (e) => {
+			if (e.target.tagName == "menupopup") {
+				document.activeElement.style.setProperty('--width-focus-border', '0');
+				document.activeElement.classList.add("hidden-focus");
+			}
+		});
+
+		// When a panel popup hides, refocus the previous element
+		// When a menupopup hides, stop hiding the focus-ring
+		document.addEventListener("popuphiding", e => {
+			if (e.target.tagName == "panel") {
+				ZoteroPane.lastFocusedElement.focus();
+			}
+			let noFocus = [...document.querySelectorAll(".hidden-focus")];
+			for (let node of noFocus) {
+				node.style.removeProperty('--width-focus-border');
+				node.classList.remove("hidden-focus");
+			}
+		});
+	}
+
 	/**
 	 * Called on window load or when pane has been reloaded after switching into or out of connector
 	 * mode
@@ -589,6 +612,7 @@ var ZoteroPane = new function()
 		catch (e) {
 			Zotero.logError(e);
 		}
+		addFocusHandlers();
 	}
 	
 	
@@ -1042,6 +1066,15 @@ var ZoteroPane = new function()
 	}
 	
 	this.handleBlur = (event) => {
+		// When focus shifts, unless we are inside of a panel, save
+		// the last focused element to be able to return focus to it when the panel closes
+		if (!event.target.closest("panel")) {
+			this.lastFocusedElement = event.target;
+			// Special treatment to focus on quick-search dropmarker inside of the shadow DOM
+			if (this.lastFocusedElement.id == "zotero-tb-search-dropmarker") {
+				this.lastFocusedElement = document.getElementById("zotero-tb-search")._searchModePopup.parentElement;
+			}
+		}
 		if (this.highlightTimer) {
 			this.highlightTimer.cancel();
 			this.highlightTimer = null;

scss/abstracts/_mixins.scss

@@ -233,10 +233,10 @@
 	components (e.g. toolbarbutton) and sometimes are too wide (e.g. around textfield on macOS).
 	Box-shadow is used to be able to set the radius.
 */
-@mixin focus-ring($width: 1px, $radius: 5px) {
+@mixin focus-ring {
 	&:focus-visible {
 	  outline: none;
-	  box-shadow: 0 0 0 $width -moz-accent-color;
-	  border-radius: $radius;
+	  box-shadow: 0 0 0 var(--width-focus-border) -moz-accent-color;
+	  border-radius: var(--radius-focus-border);
 	}
   }

scss/components/_tabsMenu.scss

@@ -2,6 +2,8 @@
 	background: var(--material-sidepane);
 	padding: 7px;
 	border-radius: 5px;
+	--width-focus-border: 3px;
+	--radius-focus-border: 5px;
 }
 
 #zotero-tabs-menu-filter {
@@ -10,7 +12,7 @@
 	border: 1px solid transparent;
 	padding-inline-start: 5px !important;
 	padding: 2px;
-	@include focus-ring(3px, 5px);
+	@include focus-ring;
 }
 
 #zotero-tabs-menu-list {
@@ -18,7 +20,7 @@
 	margin: 0;
 
 	.zotero-tabs-menu-entry {
-		@include focus-ring(3px, 5px);
+		@include focus-ring;
 		border-radius: 6px;
 		height: 22px;
 		margin: 0;

scss/elements/_editableText.scss

@@ -65,6 +65,9 @@ editable-text {
 	}
 	
 	.input {
+		--width-focus-border: 1px;
+		--radius-focus-border: 5px;
+		
 		@include focus-ring;
 		// Necessary for consistent padding, even if it's actually an <input>
 		-moz-default-appearance: textarea;

scss/elements/_itemBox.scss

@@ -7,6 +7,8 @@ item-box {
 	&[hidden] {
 		display: none;
 	}
+	--width-focus-border: 1px;
+	--radius-focus-border: 5px;
 
 	#item-box {
 		width: 100%;