diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 6e4f7e03a5f8..5bb119bbfea7 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -645,7 +645,7 @@
 /packages/devextreme/js/ui/autocomplete.d.ts                         @DevExpress/devextreme-editors
 /packages/devextreme/js/ui/autocomplete_types.d.ts                   @DevExpress/devextreme-editors
 
-/packages/devextreme/js/__internal/ui/m_autocomplete.ts              @DevExpress/devextreme-editors
+/packages/devextreme/js/__internal/ui/autocomplete.ts              @DevExpress/devextreme-editors
 
 /e2e/testcafe-devextreme/tests/accessibility/autocomplete/**  @DevExpress/devextreme-editors
 
@@ -736,7 +736,7 @@
 /packages/devextreme/js/ui/drop_down_box.d.ts                        @DevExpress/devextreme-editors
 /packages/devextreme/js/ui/drop_down_box_types.d.ts                  @DevExpress/devextreme-editors
 
-/packages/devextreme/js/__internal/ui/m_drop_down_box.ts             @DevExpress/devextreme-editors
+/packages/devextreme/js/__internal/ui/drop_down_box.ts             @DevExpress/devextreme-editors
 
 /e2e/testcafe-devextreme/tests/accessibility/dropDownBox/**   @DevExpress/devextreme-editors
 
@@ -746,7 +746,7 @@
 /packages/devextreme/js/ui/drop_down_button.d.ts                     @DevExpress/devextreme-editors
 /packages/devextreme/js/ui/drop_down_button_types.d.ts               @DevExpress/devextreme-editors
 
-/packages/devextreme/js/__internal/ui/m_drop_down_button.ts          @DevExpress/devextreme-editors
+/packages/devextreme/js/__internal/ui/drop_down_button.ts          @DevExpress/devextreme-editors
 
 /packages/devextreme-scss/scss/widgets/**/dropDownButton/**          @DevExpress/devextreme-editors
 
diff --git a/packages/devextreme/js/__internal/ui/m_autocomplete.ts b/packages/devextreme/js/__internal/ui/autocomplete.ts
similarity index 100%
rename from packages/devextreme/js/__internal/ui/m_autocomplete.ts
rename to packages/devextreme/js/__internal/ui/autocomplete.ts
diff --git a/packages/devextreme/js/__internal/ui/m_drop_down_box.ts b/packages/devextreme/js/__internal/ui/drop_down_box.ts
similarity index 99%
rename from packages/devextreme/js/__internal/ui/m_drop_down_box.ts
rename to packages/devextreme/js/__internal/ui/drop_down_box.ts
index dc46c5ef3182..f3aff53021f4 100644
--- a/packages/devextreme/js/__internal/ui/m_drop_down_box.ts
+++ b/packages/devextreme/js/__internal/ui/drop_down_box.ts
@@ -181,7 +181,7 @@ class DropDownBox<
     const selectedItem = grep(
       this.option('items') || [],
       // @ts-expect-error DataExpressionMixin must be typed
-      (item) => this._isValueEquals(this._valueGetter(item), value),
+      (item) => this._isValueEquals(this._valueGetter(item), value) as boolean,
       false,
     )[0];
 
@@ -310,7 +310,7 @@ class DropDownBox<
       }),
       _ignoreFunctionValueDeprecation: true,
       // @ts-expect-error ts-error
-      maxHeight: function () {
+      maxHeight: function (): number | undefined {
         const popupLocation = this._popupPosition?.v.location;
 
         return getElementMaxHeightByWindow(this.$element(), popupLocation);
diff --git a/packages/devextreme/js/__internal/ui/m_drop_down_button.ts b/packages/devextreme/js/__internal/ui/drop_down_button.ts
similarity index 98%
rename from packages/devextreme/js/__internal/ui/m_drop_down_button.ts
rename to packages/devextreme/js/__internal/ui/drop_down_button.ts
index cc0e28cfdcdd..bc02ac030ac8 100644
--- a/packages/devextreme/js/__internal/ui/m_drop_down_button.ts
+++ b/packages/devextreme/js/__internal/ui/drop_down_button.ts
@@ -519,30 +519,33 @@ class DropDownButton extends Widget<DropDownButtonProperties> {
     };
   }
 
-  _upDownKeyHandler() {
+  _upDownKeyHandler(): boolean {
     if (this._popup?.option('visible') && this._list) {
       this._list.focus();
     } else {
+      // eslint-disable-next-line @typescript-eslint/no-floating-promises
       this.open();
     }
 
     return true;
   }
 
-  _escHandler() {
+  _escHandler(): boolean {
+    // eslint-disable-next-line @typescript-eslint/no-floating-promises
     this.close();
     this._buttonGroup.focus();
 
     return true;
   }
 
-  _tabHandler() {
+  _tabHandler(): boolean {
+    // eslint-disable-next-line @typescript-eslint/no-floating-promises
     this.close();
 
     return true;
   }
 
-  _renderPopup() {
+  _renderPopup(): void {
     const $popup = $('<div>');
     this.$element().append($popup);
     this._popup = this._createComponent($popup, Popup, this._popupOptions());
@@ -633,7 +636,11 @@ class DropDownButton extends Widget<DropDownButtonProperties> {
       this.$element().append($buttonGroup);
     }
 
-    this._buttonGroup = this._createComponent($buttonGroup, ButtonGroup, this._getButtonGroupOptions());
+    this._buttonGroup = this._createComponent(
+      $buttonGroup,
+      ButtonGroup,
+      this._getButtonGroupOptions(),
+    );
 
     this._buttonGroup.registerKeyHandler('downArrow', this._upDownKeyHandler.bind(this));
     this._buttonGroup.registerKeyHandler('tab', this._tabHandler.bind(this));
@@ -840,7 +847,7 @@ class DropDownButton extends Widget<DropDownButtonProperties> {
       case 'showArrowIcon':
         this._updateArrowClass();
         this._renderButtonGroup();
-        this._popup && this._popup.repaint();
+        this._popup?.repaint();
         break;
       case 'width':
       case 'height':
diff --git a/packages/devextreme/js/ui/autocomplete.js b/packages/devextreme/js/ui/autocomplete.js
index 122ea4dfa0c3..4f3f313f6339 100644
--- a/packages/devextreme/js/ui/autocomplete.js
+++ b/packages/devextreme/js/ui/autocomplete.js
@@ -1,4 +1,4 @@
-import Autocomplete from '../__internal/ui/m_autocomplete';
+import Autocomplete from '../__internal/ui/autocomplete';
 
 export default Autocomplete;
 
diff --git a/packages/devextreme/js/ui/drop_down_box.js b/packages/devextreme/js/ui/drop_down_box.js
index 233d571f1c19..9cc707a76fc3 100644
--- a/packages/devextreme/js/ui/drop_down_box.js
+++ b/packages/devextreme/js/ui/drop_down_box.js
@@ -1,4 +1,4 @@
-import DropDownBox from '../__internal/ui/m_drop_down_box';
+import DropDownBox from '../__internal/ui/drop_down_box';
 
 export default DropDownBox;
 
diff --git a/packages/devextreme/js/ui/drop_down_button.js b/packages/devextreme/js/ui/drop_down_button.js
index faba4d6dadba..27d2d46f5bc8 100644
--- a/packages/devextreme/js/ui/drop_down_button.js
+++ b/packages/devextreme/js/ui/drop_down_button.js
@@ -1,4 +1,4 @@
-import DropDownButton from '../__internal/ui/m_drop_down_button';
+import DropDownButton from '../__internal/ui/drop_down_button';
 
 export default DropDownButton;