Fix crash with SetText not limiting cursor position

fixes #466

widget/entry.go

@@ -302,6 +302,15 @@ func (e *Entry) SetText(text string) {
 		e.CursorRow = 0
 		e.Unlock()
 		Renderer(e).(*entryRenderer).moveCursor()
+	} else {
+		provider := e.textProvider()
+		if e.CursorRow >= provider.rows() {
+			e.CursorRow = provider.rows() - 1
+		}
+		rowLength := provider.rowLength(e.CursorRow)
+		if e.CursorColumn >= rowLength {
+			e.CursorColumn = rowLength
+		}
 	}
 }
 

widget/entry_test.go

@@ -95,6 +95,30 @@ func TestEntry_SetTextEmptyString(t *testing.T) {
 	assert.Equal(t, 0, entry.CursorRow)
 }
 
+func TestEntry_SetText_Overflow(t *testing.T) {
+	entry := NewEntry()
+
+	assert.Equal(t, 0, entry.CursorColumn)
+
+	test.Type(entry, "test")
+	assert.Equal(t, 4, entry.CursorColumn)
+
+	entry.SetText("x")
+	assert.Equal(t, 1, entry.CursorColumn)
+
+	key := &fyne.KeyEvent{Name: fyne.KeyDelete}
+	entry.TypedKey(key)
+
+	assert.Equal(t, 1, entry.CursorColumn)
+	assert.Equal(t, "x", entry.Text)
+
+	key = &fyne.KeyEvent{Name: fyne.KeyBackspace}
+	entry.TypedKey(key)
+
+	assert.Equal(t, 0, entry.CursorColumn)
+	assert.Equal(t, "", entry.Text)
+}
+
 func TestEntry_OnKeyDown(t *testing.T) {
 	entry := NewEntry()