diff --git a/fpdfsdk/cpdfsdk_pageview.cpp b/fpdfsdk/cpdfsdk_pageview.cpp
index 2155b5d..5bdd720 100644
--- a/fpdfsdk/cpdfsdk_pageview.cpp
+++ b/fpdfsdk/cpdfsdk_pageview.cpp
@@ -259,6 +259,17 @@
   }
 }
 
+bool CPDFSDK_PageView::OnFocus(const CFX_PointF& point, uint32_t nFlag) {
+  CPDFSDK_Annot::ObservedPtr pAnnot(GetFXWidgetAtPoint(point));
+  if (!pAnnot) {
+    m_pFormFillEnv->KillFocusAnnot(nFlag);
+    return false;
+  }
+
+  m_pFormFillEnv->SetFocusAnnot(&pAnnot);
+  return true;
+}
+
 bool CPDFSDK_PageView::OnLButtonDown(const CFX_PointF& point, uint32_t nFlag) {
   CPDFSDK_Annot::ObservedPtr pAnnot(GetFXWidgetAtPoint(point));
   if (!pAnnot) {
diff --git a/fpdfsdk/cpdfsdk_pageview.h b/fpdfsdk/cpdfsdk_pageview.h
index c23aaa7..00e90d7 100644
--- a/fpdfsdk/cpdfsdk_pageview.h
+++ b/fpdfsdk/cpdfsdk_pageview.h
@@ -64,6 +64,7 @@
   CFX_WideString GetSelectedText();
   void ReplaceSelection(const CFX_WideString& text);
 
+  bool OnFocus(const CFX_PointF& point, uint32_t nFlag);
   bool OnLButtonDown(const CFX_PointF& point, uint32_t nFlag);
   bool OnLButtonUp(const CFX_PointF& point, uint32_t nFlag);
 #ifdef PDF_ENABLE_XFA
diff --git a/fpdfsdk/fpdfformfill.cpp b/fpdfsdk/fpdfformfill.cpp
index b36c1df..1b5cc48 100644
--- a/fpdfsdk/fpdfformfill.cpp
+++ b/fpdfsdk/fpdfformfill.cpp
@@ -291,6 +291,17 @@
   return pPageView->OnMouseMove(CFX_PointF(page_x, page_y), modifier);
 }
 
+FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV FORM_OnFocus(FPDF_FORMHANDLE hHandle,
+                                                 FPDF_PAGE page,
+                                                 int modifier,
+                                                 double page_x,
+                                                 double page_y) {
+  CPDFSDK_PageView* pPageView = FormHandleToPageView(hHandle, page);
+  if (!pPageView)
+    return false;
+  return pPageView->OnFocus(CFX_PointF(page_x, page_y), modifier);
+}
+
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV FORM_OnLButtonDown(FPDF_FORMHANDLE hHandle,
                                                        FPDF_PAGE page,
                                                        int modifier,
diff --git a/fpdfsdk/fpdfview_c_api_test.c b/fpdfsdk/fpdfview_c_api_test.c
index 5bad9c8..6f84f35 100644
--- a/fpdfsdk/fpdfview_c_api_test.c
+++ b/fpdfsdk/fpdfview_c_api_test.c
@@ -181,6 +181,7 @@
     CHK(FORM_DoDocumentAAction);
     CHK(FORM_DoPageAAction);
     CHK(FORM_OnMouseMove);
+    CHK(FORM_OnFocus);
     CHK(FORM_OnLButtonDown);
     CHK(FORM_OnLButtonUp);
 #ifdef PDF_ENABLE_XFA
diff --git a/public/fpdf_formfill.h b/public/fpdf_formfill.h
index 6a90140..bf385b3 100644
--- a/public/fpdf_formfill.h
+++ b/public/fpdf_formfill.h
@@ -1242,6 +1242,29 @@
                                                      double page_y);
 
 /**
+ * Function: FORM_OnFocus
+ *          This function focuses the form annotation at a given point. If the
+ *          annotation at the point already has focus, nothing happens. If there
+ *          is no annotation at the point, remove form focus.
+ * Parameters:
+ *          hHandle     -   Handle to the form fill module. Returned by
+ *                          FPDFDOC_InitFormFillEnvironment.
+ *          page        -   Handle to the page. Returned by FPDF_LoadPage.
+ *          modifier    -   Indicates whether various virtual keys are down.
+ *          page_x      -   Specifies the x-coordinate of the cursor in PDF user
+ *                          space.
+ *          page_y      -   Specifies the y-coordinate of the cursor in PDF user
+ *                          space.
+ * Return Value:
+ *          TRUE if there is an annotation at the given point and it has focus.
+ **/
+FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV FORM_OnFocus(FPDF_FORMHANDLE hHandle,
+                                                 FPDF_PAGE page,
+                                                 int modifier,
+                                                 double page_x,
+                                                 double page_y);
+
+/**
  * Function: FORM_OnLButtonDown
  *          You can call this member function when the user presses the left
  *mouse button.
diff --git a/samples/pdfium_test.cc b/samples/pdfium_test.cc
index 31235f0..b94b674 100644
--- a/samples/pdfium_test.cc
+++ b/samples/pdfium_test.cc
@@ -965,6 +965,14 @@
       } else {
         fprintf(stderr, "mousemove: bad args\n");
       }
+    } else if (tokens[0] == "focus") {
+      if (tokens.size() == 3) {
+        int x = atoi(tokens[1].c_str());
+        int y = atoi(tokens[2].c_str());
+        FORM_OnFocus(form, page, 0, x, y);
+      } else {
+        fprintf(stderr, "focus: bad args\n");
+      }
     } else {
       fprintf(stderr, "Unrecognized event: %s\n", tokens[0].c_str());
     }
diff --git a/testing/resources/javascript/mouse_events.evt b/testing/resources/javascript/mouse_events.evt
new file mode 100644
index 0000000..5710506
--- /dev/null
+++ b/testing/resources/javascript/mouse_events.evt
@@ -0,0 +1,19 @@
+# Mouse in, mouse out.
+mousemove,125,225
+mousemove,125,100
+# Mouse in, click in field.
+mousemove,125,225
+mousedown,left,125,225
+mouseup,left,125,225
+# Mouse out, click elsewhere.
+# This should trigger an On Blur event. (Bug 881)
+mousemove,125,100
+mousedown,left,125,100
+mouseup,left,125,100
+# Mouse in, focus.
+mousemove,125,225
+focus,125,225
+# Mouse out, unfocus.
+# This should trigger an On Blur event. (Bug 881)
+mousemove,125,100
+focus,125,100
diff --git a/testing/resources/javascript/mouse_events.in b/testing/resources/javascript/mouse_events.in
new file mode 100644
index 0000000..a72162a
--- /dev/null
+++ b/testing/resources/javascript/mouse_events.in
@@ -0,0 +1,92 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+  /AcroForm 4 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 1
+  /Kids [
+    3 0 R
+  ]
+>>
+endobj
+% Page number 0.
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources <<
+    /Font <</F1 20 0 R>>
+  >>
+  /Annots [ 5 0 R ]
+  /Contents [21 0 R]
+  /MediaBox [0 0 612 792]
+>>
+% Forms
+{{object 4 0}} <<
+  /Fields [5 0 R]
+>>
+% Field with actions:
+% Cursor enter: E
+% Cursor exit: X
+% Mouse down: D
+% Mouse up: U
+% Focus: Fo
+% Blur: Bl
+{{object 5 0}} <<
+ /FT /Tx
+ /T (MyField)
+ /Type /Annot
+ /Subtype /Widget
+ /Rect [100 200 150 250]
+ /AA <<
+   /E 10 0 R
+   /X 11 0 R
+   /D 12 0 R
+   /U 13 0 R
+   /Fo 14 0 R
+   /Bl 15 0 R
+ >>
+>>
+{{object 10 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("enter"\);)
+>>
+endobj
+{{object 11 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("exit"\);)
+>>
+endobj
+{{object 12 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("down"\);)
+>>
+endobj
+{{object 13 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("up"\);)
+>>
+endobj
+{{object 14 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("focus"\);)
+>>
+endobj
+{{object 15 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS (app.alert\("blur"\);)
+>>
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF
diff --git a/testing/resources/javascript/mouse_events_expected.txt b/testing/resources/javascript/mouse_events_expected.txt
new file mode 100644
index 0000000..3d9b8b6
--- /dev/null
+++ b/testing/resources/javascript/mouse_events_expected.txt
@@ -0,0 +1,10 @@
+Alert: enter
+Alert: exit
+Alert: enter
+Alert: down
+Alert: focus
+Alert: up
+Alert: exit
+Alert: enter
+Alert: focus
+Alert: exit
diff --git a/testing/tools/test_runner.py b/testing/tools/test_runner.py
index 9524b74..86e0563 100644
--- a/testing/tools/test_runner.py
+++ b/testing/tools/test_runner.py
@@ -115,7 +115,7 @@
     txt_path = os.path.join(self.working_dir, input_root + '.txt')
 
     with open(txt_path, 'w') as outfile:
-      cmd_to_run = [self.pdfium_test_path, pdf_path]
+      cmd_to_run = [self.pdfium_test_path, '--send-events', pdf_path]
       subprocess.check_call(cmd_to_run, stdout=outfile)
 
     cmd = [sys.executable, self.text_diff_path, expected_txt_path, txt_path]