diff --git a/chrome/content/zotero/elements/collapsibleSection.js b/chrome/content/zotero/elements/collapsibleSection.js
index 015e7e7bda..d2ffcae73b 100644
--- a/chrome/content/zotero/elements/collapsibleSection.js
+++ b/chrome/content/zotero/elements/collapsibleSection.js
@@ -43,7 +43,7 @@
 		set open(newOpen) {
 			newOpen = !!newOpen;
 			let oldOpen = this.open;
-			if (oldOpen === newOpen || this.empty) return;
+			if (oldOpen === newOpen || this.empty || !this.collapsible) return;
 			this.render();
 			
 			// Force open before getting scrollHeight, so we get the right value
@@ -106,6 +106,19 @@
 			this.setAttribute('summary', val);
 		}
 		
+		get collapsible() {
+			return !this.getAttribute("no-collapse");
+		}
+
+		set collapsible(val) {
+			if (val) {
+				this.removeAttribute('no-collapse');
+			}
+			else {
+				this.setAttribute('no-collapse', val);
+			}
+		}
+		
 		static get observedAttributes() {
 			return ['open', 'empty', 'label', 'summary', 'extra-buttons'];
 		}
diff --git a/chrome/content/zotero/elements/itemPaneSection.js b/chrome/content/zotero/elements/itemPaneSection.js
index d5651ffef7..1cf01e442a 100644
--- a/chrome/content/zotero/elements/itemPaneSection.js
+++ b/chrome/content/zotero/elements/itemPaneSection.js
@@ -84,6 +84,14 @@ class ItemPaneSectionElementBase extends XULElementBase {
 			this._section.open = val;
 		}
 	}
+
+	get collapsible() {
+		return this._section.collapsible;
+	}
+
+	set collapsible(val) {
+		this._section.collapsible = !!val;
+	}
 	
 	connectedCallback() {
 		super.connectedCallback();
diff --git a/chrome/content/zotero/elements/tagsBox.js b/chrome/content/zotero/elements/tagsBox.js
index c5579ebec3..892697d487 100644
--- a/chrome/content/zotero/elements/tagsBox.js
+++ b/chrome/content/zotero/elements/tagsBox.js
@@ -342,6 +342,18 @@
 					focusField.focus();
 				}
 			}
+			else if (event.key == "Tab" && !event.shiftKey) {
+				// On tab from the last empty tag row, the minus icon will be focused
+				// and the row will be immediately removed in this.saveTag, so focus will be lost.
+				// To avoid that, on tab from the last tag input that is empty, focus the next
+				// element after the tag row.
+				let allTags = [...this.querySelectorAll(".row")];
+				let isLastTag = target.closest(".row") == allTags[allTags.length - 1];
+				if (isLastTag && !target.closest("editable-text").value.length) {
+					Services.focus.moveFocus(window, target.closest(".row").lastChild, Services.focus.MOVEFOCUS_FORWARD, 0);
+					event.preventDefault();
+				}
+			}
 		};
 
 		// Intercept paste, check for newlines, and convert textbox
diff --git a/chrome/content/zotero/xpcom/reader.js b/chrome/content/zotero/xpcom/reader.js
index f1317910a2..c14655ed1e 100644
--- a/chrome/content/zotero/xpcom/reader.js
+++ b/chrome/content/zotero/xpcom/reader.js
@@ -896,30 +896,43 @@ class ReaderInstance {
 	}
 
 	_openTagsPopup(item, x, y) {
-		let menupopup = this._window.document.createXULElement('menupopup');
-		menupopup.addEventListener('popuphidden', function (event) {
-			if (event.target === menupopup) {
-				menupopup.remove();
+		let tagsPopup = this._window.document.createXULElement('panel');
+		tagsPopup.addEventListener('popuphidden', function (event) {
+			if (event.target === tagsPopup) {
+				tagsPopup.remove();
 			}
 		});
-		menupopup.className = 'tags-popup';
-		menupopup.setAttribute('ignorekeys', true);
+		tagsPopup.addEventListener('keydown', function (event) {
+			if (event.key == "Escape") {
+				tagsPopup.hidePopup();
+			}
+		});
+		tagsPopup.className = 'tags-popup';
 		let tagsbox = this._window.document.createXULElement('tags-box');
-		menupopup.appendChild(tagsbox);
+		tagsPopup.appendChild(tagsbox);
 		tagsbox.setAttribute('flex', '1');
-		this._popupset.appendChild(menupopup);
+		this._popupset.appendChild(tagsPopup);
 		let rect = this._iframe.getBoundingClientRect();
 		x += rect.left;
 		y += rect.top;
 		tagsbox.editable = true;
 		tagsbox.item = item;
 		tagsbox.render();
-		menupopup.openPopup(null, 'before_start', x, y, true);
-		setTimeout(() => {
+		// remove unnecessary tabstop from the section header
+		tagsbox.querySelector(".head").removeAttribute("tabindex");
+		tagsPopup.addEventListener("popupshown", (_) => {
+			// Ensure tagsbox is open
+			tagsbox.open = true;
 			if (tagsbox.count == 0) {
 				tagsbox.newTag();
 			}
+			else {
+				// Focus + button
+				Services.focus.setFocus(tagsbox.querySelector("toolbarbutton"), Services.focus.FLAG_NOSHOWRING);
+			}
+			tagsbox.collapsible = false;
 		});
+		tagsPopup.openPopup(null, 'before_start', x, y, true);
 	}
 
 	async _openContextMenu({ x, y, itemGroups }) {
diff --git a/scss/components/_reader.scss b/scss/components/_reader.scss
index 0ab71eedab..e853871b5e 100644
--- a/scss/components/_reader.scss
+++ b/scss/components/_reader.scss
@@ -1,12 +1,7 @@
-menupopup.tags-popup {
+.tags-popup {
 	font: inherit;
 	min-width: 300px;
-	padding-inline: 8px;
-
-	@media (-moz-platform: windows) {
-		& > tags-box {
-			// padding-inline does not work on Windows
-			margin-inline: 8px;
-		}
+	& > tags-box {
+		padding-inline: 8px;
 	}
 }