add a button for XY Plot to fill in available values for axes that support this

style.css

@@ -644,7 +644,7 @@ canvas[key="mask"] {
     max-width: 2.5em;
     min-width: 2.5em !important;
     height: 2.4em;
-    margin: 0.55em 0;
+    margin: 0.55em 0.7em 0.55em 0;
 }
 
 #quicksettings .gr-button-tool{
@@ -717,16 +717,6 @@ footer {
     line-height: 2.4em;
 }
 
-#xy_grid_button_column {
-    min-width: 38px !important;
-}
-
-#xy_grid_button_column button {
-    height: 100%;
-    margin-bottom: 0.7em;
-    margin-left: 1em;
-}
-
 /* The following handles localization for right-to-left (RTL) languages like Arabic.
 The rtl media type will only be activated by the logic in javascript/localization.js.
 If you change anything above, you need to make sure it is RTL compliant by just running