DictQuickLookup: hold prev/next buttons go to first/last result

frontend/ui/widget/dictquicklookup.lua

@@ -461,6 +461,9 @@ function DictQuickLookup:update()
                     callback = function()
                         self:changeToPrevDict()
                     end,
+                    hold_callback = function()
+                        self:changeToFirstDict()
+                    end,
                 },
                 {
                     text = self:getHighlightText(),
@@ -480,6 +483,9 @@ function DictQuickLookup:update()
                     callback = function()
                         self:changeToNextDict()
                     end,
+                    hold_callback = function()
+                        self:changeToLastDict()
+                    end,
                 },
             },
             {
@@ -846,6 +852,18 @@ function DictQuickLookup:changeToNextDict()
     end
 end
 
+function DictQuickLookup:changeToFirstDict()
+    if self:isPrevDictAvaiable() then
+        self:changeDictionary(1)
+    end
+end
+
+function DictQuickLookup:changeToLastDict()
+    if self:isNextDictAvaiable() then
+        self:changeDictionary(#self.results)
+    end
+end
+
 function DictQuickLookup:changeDictionary(index)
     if not self.results[index] then return end
     self.dict_index = index