AG-16842 fix extra border on columns tool panel (ag-grid#13272)

Author: BernieSumption

community-modules/styles/src/internal/base/parts/_columns-tool-panel.scss

@@ -29,8 +29,11 @@
     }
 
     .ag-column-panel-column-select {
-        border-bottom: var(--ag-borders-secondary) var(--ag-secondary-border-color);
         border-top: var(--ag-borders-secondary) var(--ag-secondary-border-color);
+
+        &:not(.ag-last-visible-child) {
+            border-bottom: var(--ag-borders-secondary) var(--ag-secondary-border-color);
+        }
     }
 
     .ag-column-group-icons,

community-modules/styles/src/internal/themes/quartz/_index.scss

@@ -143,7 +143,10 @@
 
     .ag-column-panel-column-select {
         border-top: none;
-        border-bottom: 1px solid var(--ag-secondary-border-color);
+
+        &:not(.ag-last-visible-child) {
+            border-bottom: 1px solid var(--ag-secondary-border-color);
+        }
     }
 
     .ag-filter-toolpanel-search {

packages/ag-grid-enterprise/src/columnToolPanel/columnToolPanel.css

@@ -16,7 +16,7 @@
     margin-left: var(--ag-widget-container-horizontal-padding);
 }
 
-.ag-column-panel-column-select {
+.ag-column-panel-column-select:where(:not(.ag-last-visible-child)) {
     border-bottom: var(--ag-tool-panel-separator-border);
 }
 

packages/ag-grid-enterprise/src/columnToolPanel/columnToolPanel.ts

@@ -184,7 +184,9 @@ export class ColumnToolPanel extends Component implements IColumnToolPanel, IToo
             }
             const eGui = panel.getGui();
             panel.toggleResizable(
-                !eGui.classList.contains('ag-last-column-drop') && !eGui.classList.contains('ag-hidden')
+                !eGui.classList.contains('ag-last-column-drop') &&
+                    !eGui.classList.contains('ag-hidden') &&
+                    !eGui.classList.contains('ag-last-visible-child')
             );
         }
     }
@@ -205,6 +207,7 @@ export class ColumnToolPanel extends Component implements IColumnToolPanel, IToo
             lastVisible.classList.add('ag-last-column-drop');
         }
 
+        this.primaryColsPanel.getGui().classList.toggle('ag-last-visible-child', !lastVisible);
         this.setResizers();
     }