[add] what's new and grid docs' updates for v9.2.4

Author: mafanya23

docs/grid/api/gridcolumn_properties/gridcolumn_header_property.md

@@ -36,7 +36,7 @@ header: [
             filter?: (item, input: string) => boolean,
             multiselection?: boolean,
             readonly?: boolean,
-            placeholder?: string,
+            placeholder?: string, // sets an input placeholder for `comboFilter` and `inputFilter`
             virtual?: boolean, // true by default
             template?: function
         },
@@ -79,7 +79,7 @@ Each header object may include:
             <td><a href="../../../configuration/#headerfooter-filters"><b>content</b></a></td><td>(optional) additional content of a header, which can be one of the filters: "inputFilter" | "selectFilter" | "comboFilter"</td>
         </tr>
         <tr>
-            <td><a href="../../../configuration/#headerfooter-filters"><b>filterConfig</b></a></td><td>(optional) a configuration object for <b>"comboFilter"</b>. It can contain a set of properties:<ul><li><b>filter</b> - (optional) sets a custom function for filtering Combo Box options</li><li><b>multiselection</b> - (optional) enables selection of multiple options</li><li><b>readonly</b> - (optional) makes ComboBox readonly (it is only possible to select options from the list, without entering words in the input). The default value of the <b>readonly</b> property depends on the following conditions:<ul><li>the `readonly:true` is set as a default value, if `htmlEnable:true` is set for a column and there is no template specified for a column</li><li>in all other cases, `readonly:false` is set by default</li></ul></li><li><b>placeholder</b> - (optional) sets a placeholder in the input of ComboBox</li><li><b>virtual</b> - (optional) enables dynamic loading of data on scrolling the list of options, <i>true</i> by default</li><li><b>template</b> - (optional) a function which returns a template with content for the filter options. Takes an option item as a parameter:<ul><li><b>item</b> - (object) an option item</li></ul></li></ul></td>
+            <td><a href="../../../configuration/#headerfooter-filters"><b>filterConfig</b></a></td><td>(optional) a configuration object for <b>"comboFilter"</b> and <b>"inputFilter"</b> <br><br> a configuration object for <b>"comboFilter"</b> can contain a set of properties:<ul><li><b>filter</b> - (optional) sets a custom function for filtering Combo Box options</li><li><b>multiselection</b> - (optional) enables selection of multiple options</li><li><b>readonly</b> - (optional) makes ComboBox readonly (it is only possible to select options from the list, without entering words in the input). The default value of the <b>readonly</b> property depends on the following conditions:<ul><li>the `readonly:true` is set as a default value, if `htmlEnable:true` is set for a column and there is no template specified for a column</li><li>in all other cases, `readonly:false` is set by default</li></ul></li><li><b>placeholder</b> - (optional) sets a placeholder in the input of ComboBox</li><li><b>virtual</b> - (optional) enables dynamic loading of data on scrolling the list of options, <i>true</i> by default</li><li><b>template</b> - (optional) a function which returns a template with content for the filter options. Takes an option item as a parameter:<ul><li><b>item</b> - (object) an option item</li></ul></li></ul> <br> a configuration object for <b>"inputFilter"</b> can contain the following property: <ul><li><b>placeholder</b> - (optional) sets a placeholder in the input</li></ul> </td>
         </tr>
         <tr>
             <td><a href="../../../configuration/#customizing-headerfooter-filters"><b>customFilter</b></a> </td><td>(optional) a custom function for extended filtering. It takes two parameters:<ul><li><b>item</b> - (required) a data item the value of which should be compared</li><li> <b>input</b> - (required) the value of the option selected in the filter</li></ul>and returns <i>true/false</i> to specify whether the data item should be displayed in the grid after filtering</td>

docs/grid/configuration.md

@@ -1386,6 +1386,18 @@ There are three types of filters that you can specify in the header/footer conte
 
 **Related sample**: [Grid. Header filters (comboFilter, inputFilter, selectFilter)](https://snippet.dhtmlx.com/4qz8ng3c)
 
+If you specify **inputFilter** as the header or footer content of a column, you can set a configuration object for it via the `filterConfig` property. The configuration object may contain the **placeholder** property that sets a placeholder in the input:
+
+~~~jsx
+{ 
+    width: 160, id: "population", 
+    header: [
+        { text: "Population" }, 
+        { content: "inputFilter", filterConfig: { placeholder: "Type something" } }
+    ]
+}
+~~~
+
 - **selectFilter** - allows end users to filter data of a column by choosing an option from a presented dropdown list
 
 ~~~jsx
@@ -1412,7 +1424,7 @@ There are three types of filters that you can specify in the header/footer conte
 
 **Related sample**: [Grid. Header filters (comboFilter, inputFilter, selectFilter)](https://snippet.dhtmlx.com/4qz8ng3c)
 
-If you specify **comboFilter** as the header or footer content of a column, you can set an additional config with properties for it.
+If you specify **comboFilter** as the header or footer content of a column, you can set an additional config with properties for it via the `filterConfig` property:
 
 ~~~jsx {8}
 const grid = new dhx.Grid("grid_container", {

docs/whatsnew.md

@@ -8,6 +8,18 @@ description: You can explore what's new in DHTMLX Suite and its release history
 
 Before updating DHTMLX to the latest version, please check the [Migration to Newer Versions](migration.md) guide to avoid possible breakdowns.
 
+## Version 9.2.4
+
+Released on November 17, 2025
+
+### Fixes
+
+- Form. The `getValue()` method returns an empty string for a Combo option if its ID is specified as 0 (zero)
+- Grid. `comboFilter` displays all the options even if its `filterConfig` configuration object is initialized without the `filter` property
+- Grid. Incorrect date format in an exported Excel file
+- Grid. The ability to [specify a placeholder in the `inputFilter` via the `filterConfig` configuration object](/grid/configuration/#headerfooter-filters) is added
+- Tree. Incorrect dropping behavior when the `dropBehavior:sibling` property is set in the Tree configuration
+
 ## Version 9.2.3
 
 Released on October 21, 2025