(core) Select all functionality by clicking the upper left margin corner

Summary: Select all functionality by clicking the upper left margin corner

Test Plan: Browser test created

Reviewers: dsagal, paulfitz

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2793

app/client/components/GridView.css

@@ -146,6 +146,7 @@
   top: 1px; /* go under 1px border on scrollpane */
   border-bottom: 1px solid lightgray;
   z-index: 3;
+  cursor: pointer;
 }
 
 .scroll_shadow_left {

app/client/components/GridView.js

@@ -736,7 +736,10 @@ GridView.prototype.buildDom = function() {
 
     // Corner, bars and shadows
     // Corner and shadows (so it's fixed to the grid viewport)
-    self._cornerDom = dom('div.gridview_data_corner_overlay'),
+    self._cornerDom = dom(
+      'div.gridview_data_corner_overlay',
+      dom.on('click', () => this.selectAll()),
+    ),
     dom('div.scroll_shadow_top', kd.show(this.scrollShadow.top)),
     dom('div.scroll_shadow_left', kd.show(this.scrollShadow.left)),
     dom('div.gridview_header_backdrop_left'), //these hide behind the actual headers to keep them from flashing

test/nbrowser/gristUtils.ts

@@ -728,7 +728,6 @@ export async function addNewTable() {
   await waitForServer();
 }
 
-
 // Add a new page using the 'Add New' menu and wait for the new page to be shown.
 export async function addNewPage(typeRe: RegExp, tableRe: RegExp, summarize?: RegExp[]) {
   const url = await driver.getCurrentUrl();