Make opened tabs menu scrollable (#3833)

- If there are too many tabs opened to fit onto the screen,
the tabs menu can be scrolled
- When tabs menu is opened, scroll to the selected tab
- Use margins instead of padding to that the scrollbar does not
overlap with the cross button
- Make sure that if the tabs menu is long, there will
be a gap between it's top/bottom and the edge of the
screen
- On linux, screen.availTop and screen.availHeight are not always
correct and the menu can go outside of what is supposed to be
the available screen area. Special treatment for those
edge cases

chrome/content/zotero/tabs.js

@@ -979,12 +979,62 @@ var Zotero_Tabs = new function () {
 		let menuFilter = document.getElementById('zotero-tabs-menu-filter');
 		menuFilter.value = "";
 		this._tabsMenuFilter = "";
+		this.tabsMenuList.closest("panel").style.removeProperty('max-height');
 	};
 
 	this.handleTabsMenuShown = function (_) {
 		focusTabsMenuEntry(0);
 	};
 
+	this.handleTabsMenuShowing = function (_) {
+		this.refreshTabsMenuList();
+
+		// Make sure that if the menu is very long, there is a small
+		// gap left between the top/bottom of the menu and the edge of the screen
+		let valuesAreWithinMargin = (valueOne, valueTwo, margin) => {
+			return Math.abs(valueOne - valueTwo) <= margin;
+		};
+		let panel = document.getElementById("zotero-tabs-menu-panel");
+		let panelRect = panel.getBoundingClientRect();
+		const gapBeforeScreenEdge = 25;
+		let absoluteTabsMenuTop = window.screenY - panelRect.height + panelRect.bottom;
+		let absoluteTabsMenuBottom = window.screenY + panelRect.height + panelRect.top;
+
+		// On windows, getBoundingClientRect does not give us correct top and bottom values
+		// until popupshown, so instead use the anchor's position
+		if (Zotero.isWin) {
+			let anchor = document.getElementById("zotero-tb-tabs-menu");
+			let anchorRect = anchor.getBoundingClientRect();
+			absoluteTabsMenuTop = window.screenY - panelRect.height + anchorRect.top;
+			absoluteTabsMenuBottom = window.screenY + panelRect.height + anchorRect.bottom;
+		}
+		// screen.availTop is not always right on Linux, so ignore it
+		let availableTop = Zotero.isLinux ? 0 : screen.availTop;
+
+		// Check if the end of the tabs menu is close to the edge of the screen
+		let atTopScreenEdge = valuesAreWithinMargin(absoluteTabsMenuTop, availableTop, gapBeforeScreenEdge);
+		let atBottomScreenEdge = valuesAreWithinMargin(absoluteTabsMenuBottom, screen.availHeight + availableTop, gapBeforeScreenEdge);
+
+		let gap;
+		// Limit max height of the menu to leave the specified gap till the screen's edge.
+		// Due to screen.availTop behavior on linux, the menu can go outside of what is supposed
+		// to be the available screen area, so special treatment for those edge cases.
+		if (atTopScreenEdge || (Zotero.isLinux && absoluteTabsMenuTop < 0)) {
+			gap = gapBeforeScreenEdge - (absoluteTabsMenuTop - availableTop);
+		}
+		if (atBottomScreenEdge || (Zotero.isLinux && absoluteTabsMenuBottom > screen.availHeight)) {
+			gap = gapBeforeScreenEdge - (screen.availHeight + availableTop - absoluteTabsMenuBottom);
+		}
+		if (gap) {
+			panel.style.maxHeight = `${panelRect.height - gap}px`;
+		}
+		// Try to scroll selected tab into the center
+		let selectedTab = this.tabsMenuList.querySelector(".selected");
+		if (selectedTab) {
+			selectedTab.scrollIntoView({ block: 'center' });
+		}
+	};
+
 	/**
 	 * Record the value of the filter
 	 */

chrome/content/zotero/zoteroPane.xhtml

@@ -840,7 +840,7 @@
 			<div xmlns="http://www.w3.org/1999/xhtml" class="zotero-tb-separator"></div>
 			<panel id="zotero-tabs-menu-panel" type="arrow" 
 					onpopuphiding="Zotero_Tabs.handleTabsMenuHiding(event)"
-					onpopupshowing="Zotero_Tabs.refreshTabsMenuList()"
+					onpopupshowing="Zotero_Tabs.handleTabsMenuShowing(event)"
 					onpopupshown="Zotero_Tabs.handleTabsMenuShown(event)"
 					onkeydown="Zotero_Tabs.handleTabsMenuKeyPress(event)"
 					tabindex="-1"

scss/components/_tabsMenu.scss

@@ -6,13 +6,16 @@
 #zotero-tabs-menu-wrapper {
 	width: 350px;
 	background: var(--material-sidepane);
-	padding: 7px;
+	padding: 0;
 	border-radius: 5px;
 	--width-focus-border: 2px;
+	display: flex;
+	flex-direction: column;
+	min-height: 0;
 }
 
 #zotero-tabs-menu-filter {
-	margin: 0 0 7px 0;
+	margin: 7px 7px 2px 7px;
 	border-radius: 5px;
 	border: 1px solid transparent;
 	padding-inline-start: 5px !important;
@@ -26,10 +29,14 @@
 #zotero-tabs-menu-list {
 	appearance: none;
 	margin: 0;
+	overflow-x: hidden;
+	overflow-y: scroll;
+	scrollbar-width: thin;
+	padding: 5px 0;
 
 	.row {
 		display: flex;
-		padding-inline-start: 4px;
+		padding-inline: 4px;
 	}
 
 	.zotero-tabs-menu-entry {