Feedback Feature Request: Control of mobile TouchScreenKeyboard visibility on focus change

I posted on the forums about this previously and it was suggested to me that I submit it as a bug fix/feature request. I submitted a bug report and was redirected to the forums once again so here I am with this feature request:

(On an android device) I would like a way to keep the mobile TouchScreenKeyboard open when focus changes to a different UI element. This would include being able to interact with unity in the visible area while the keyboard remains on screen.

The current implementation forces the mobile TouchScreenKeyboard to close when its focus is lost. This is not ideal and not consistent with keyboard behavior in most other android apps. This prevents me from creating a smooth experience where, for example, the user can input text which is used to show results of a search. When the user tries to select a result, the input is ignored and the keyboard goes away. The user cannot interact with a scroll view or any buttons while the keyboard is on screen. Almost all android chat interfaces allow users to do this, I would love have this functionality in Unity to give the user a predictable and consistent UI experience.

Here's a google drive link to a sample project showing this problem using Unity 2020.1.0b13. Just run on an android device and tap the inputfield. When you try to interact with the scroll view or button, the input is ignored and the keyboard hides.

Thank you!

 

up

 

https://forum.unity.com/threads/keyboard-hides-when-tap-anywhere.784280/
https://forum.unity.com/threads/input-problem-when-keyboard-is-opened-on-android.354864/
https://forum.unity.com/threads/android-keyboard-blocks-touches.913532/#post-5988215
https://forum.unity.com/threads/receiving-touch-events-while-on-screen-keyboard-is-open.669352/
https://forum.unity.com/threads/any-way-to-prevent-inputfield-from-losing-focus-on-tap.690568/

 

Thank you for doing so. I am also facing this issue. Without a fix, Unity is literally unable to support a professional chat app or any app that relies on messaging.

This is quite a severe issue affecting many including Unity's adoption. Please let us know when there is a fix. Until then, we can either create a custom keyboard (which is far from ideal since the majority of users I speak to say they hate custom keyboards and prefer the one that they use daily) or to uncheck the "Hide Mobile Input" option which results in an input system that is so far removed from any professional/respectable app.

Thank you for your time. Quite literally praying this can get fixed asap or else we are at a loss of what to do.

 

Any update on this?

I found this hack mentioned elsewhere on the forums that seems like it might help:
https://github.com/mopsicus/UnityMobileInput

Gonna give it a shot and report back

Edit: looks like this doesn't work for TMP Input fields. welp, still waiting for this

 

up

 

Up, the ScreenKeyboard implementation on Android has been notorious for years. It makes input UX on Android universally bad. Users have been requesting, begging, and scolding for changes for a longggggggggggggggggggg time to no avail.

• Form filling (for registration and such)
• Chat behavior/app (need to tap 2 times to send a message)
• Every UIs that uses more than 2 InputField
• Every time user needs to interact with game elements or other UI when ScreenKeyboard is shown.
• Screen Keyboard mess up the game life cycle because OnApplicationFocus got called for no good reason.
• Basically, I think there is no Android game that uses InputField and does not suffer from the weirdness of ScreenKeyboard. Considering that Unity is most known for its dominance over the mobile market....

I understand that this is not the native behavior of Android's keyboard but instead of wasting developers' hours every time someone needs to implement something more complex with InputField, why couldn't you make a hack for us? this is not even a feature but the most basic functionality that we expect from the engine, which is best known for its mobile game development.

I have been circumventing this with paid 3rd party tools but I hope for a better future of Unity where this particularly nasty papercut will be gone.

 

Has there been any progress on this, or are we forced to use 3rd party assets?

 

Another bump.

 

Is there any update on this? Implementing a chat feature and have tried almost everything.

 

@D4RKST4R007

I bought this asset https://assetstore.unity.com/packages/tools/integration/osk-on-screen-keyboard-77689 ...

It is a little dated but it was easy enough for me to update the UI and it has some code I was able to easily edit...

What I did for my needs is disable the built in keyboard and then just used this... no not ideal but it does give me full control over the keyboard....

 

bump

 

So does that mean at least one someone is working on this?

Can we get an updated comment about this so we know you guys still have eyes on it?

Thanks

 

Up +1

 

Up +1

 

Has anyone tried this solution with TMP in newer versions?

 

Cross-post for visibility - a solution to android:

 

I just tried it, and when setting closeKeyboardOnOutsideTap to false, tapping outside of the keyboard still hides it on 2020.3.26f1.

 

Yea this is pretty buggy atm - I just tested and it only works when you click on the input field again (as I think it just reopens it instantly). Anywhere else and it closes - but it does let you click stuff while closing the keyboard. So let's say you have a back button in unity UI, you can now click that and it will actually fire, but the keyboard will still close.

Edit: Looks like the keyboard is hidden on pointer down.

Edit 2: Unity 2021.2.8f1

 

@Tomas1856 uGUI

 

@Tomas1856 Any update on this?

 

@Tomas1856 I feel kinda dumb but how do you set closeKeyboardOnOutsideTap to false? It doesn't seem to excist when I type it (2021.1.12f1)

 

Hey there, I appreciate the work being done to support this feature. Thank you! This is a great step towards it, I can now interact with unity while the keyboard is open.

It's still not perfect though as Nyankoooo and TheVirtualMunk have said. My interaction is limited to a single tap, which forces the keyboard to close. This means, for example, no scrolling through a list of results that are populated as you type. A common desired end result for a feature like this I would say. If there's a way to keep the keyboard open as input is passed through, this would be 100% solved!

 

Facing the same problem so annoying. Pleas resolve this.

 

I have the same issue. "closeKeyboardOnOutsideTap " does not completely solve the problem.
I would like a way to keep the mobile TouchScreenKeyboard open while focus is on the inputfield.

 

I am also facing the same problem and very confused.
In my app, the operability of this UI is one of the important functions.
I think Unity is a great service for creating games.
By all means, I would like to ask you to improve the UI.
Hey Unity, do you have any plans to fix this?

 

Unity mobile keyboard controller bridge is horrible! For more then 6 years you are focused on mobile app development and still can't make is work well with full functionality. We have to use custom native plugins to make it work well. Furthermore, on Android device TouchKeyboard NEVER shows the keyboard height. Wtf?

 

If I set

Code (CSharp):

1. TouchScreenKeyboard.Android.consumesOutsideTouches = true;

in 2021.3 and tap into the multiline input field, the mobile keyboard shows up on the screen. When I tap again onto the mobile screen, somewhere in the app, the mobile keyboard does not disappear; it stays open. This is great, but... the app does not react on any taps anymore.

This is a bit unfortunate, as I cannot even move the cursor in the input field to a different position with a touch while the keyboard is open. I need to close the keyboard, and tap again, hoping that my tap is accurate enough to place the cursor accurately.

Great so far, but still room for improvement, certainly.

 

Apologies; typo in my reply above:
The app does react on taps, but the input field doesn't.
Sorry; I can't edit the post; get a spam warning.

 

I just had to edit the text mesh pro package. It's quite an annoying solution, I'm surprised that we can't have full control of the keyboard easily without having to make our own.. Interesting eh?

 

Hi there,
I think I found the culprit that prevents the selection if Hide Input Mobile = true with a TMP_InputField and the option TouchScreenKeyboard.Android.consumesOutsideTouches = true.
In my opinion there is a ! missing in front of m_HideMobileInput on line 1623 from TMP_InputField.
To solve the problem temporarily, I created a class that overrides TMP_InputField and therefore calls Reflection.
It's not a long term solution but it do the trick for the moment.

Code (CSharp):

1.  
2. using UnityEditor;
3. using TMPro.EditorUtilities;
4. using TMPro;
5.  
6. [CustomEditor(typeof(TMP_TouchInputField))]
7. public class TMP_TouchInputFieldEditor : TMP_InputFieldEditor
8. {
9.     #region Context menu
10.     [MenuItem("CONTEXT/TMP_InputField/Convert To TMP_TouchInputField", true)]
11.     private static bool _ConvertToTMP_TouchInputField(MenuCommand command)
12.     {
13.        return EditorUtils.CanConvertTo<TMP_TouchInputField>(command.context);
14.     }
15.  
16.     [MenuItem("CONTEXT/TMP_InputField/Convert To TMP_TouchInputField", false)]
17.     private static void ConvertToTMP_TouchInputField(MenuCommand command)
18.     {
19.        EditorUtils.ConvertTo<TMP_TouchInputField>(command.context);
20.     }
21.  
22.     [MenuItem("CONTEXT/TMP_TouchInputField/Convert To TMP_InputField", true)]
23.     private static bool _ConvertToTMP_InputField(MenuCommand command)
24.     {
25.         return EditorUtils.CanConvertTo<TMP_InputField>(command.context);
26.     }
27.  
28.     [MenuItem("CONTEXT/TMP_TouchInputField/Convert To TMP_InputField", false)]
29.     private static void ConvertToTMP_InputField(MenuCommand command)
30.     {
31.         EditorUtils.ConvertTo<TMP_InputField>(command.context);
32.     }
33.    #endregion
34. }
35.  
36. public static class EditorUtils
37.     {
38.         /// <summary>
39.         /// Verify whether it can be converted to the specified component.
40.         /// </summary>
41.         public static bool CanConvertTo<T>(Object context) where T : MonoBehaviour
42.         {
43.             return context && context.GetType() != typeof(T);
44.         }
45.  
46.         /// <summary>
47.         /// Convert to the specified component.
48.         /// </summary>
49.         public static void ConvertTo<T>(Object context) where T : MonoBehaviour
50.         {
51.             if (PrefabUtility.IsPartOfVariantPrefab(context))
52.             {
53.                 Debug.LogError("Cannot convert a component from a variant prefab!");
54.                 return;
55.             }
56.  
57.             var target = context as MonoBehaviour;
58.             var so = new SerializedObject(target);
59.             so.Update();
60.  
61.             var oldEnable = target.enabled;
62.             target.enabled = false;
63.  
64.             // Find MonoScript of the specified component.
65.             foreach (var script in Resources.FindObjectsOfTypeAll<MonoScript>())
66.             {
67.                 if (script.GetClass() != typeof(T))
68.                     continue;
69.  
70.                 // Set 'm_Script' to convert.
71.                 so.FindProperty("m_Script").objectReferenceValue = script;
72.                 so.ApplyModifiedProperties();
73.                 break;
74.             }
75.  
76.             (so.targetObject as MonoBehaviour).enabled = oldEnable;
77.         }
78.     }
79.  
80.  

Code (CSharp):

1. using UnityEngine;
2. using TMPro;
3. using UnityEngine.EventSystems;
4. using System.Reflection;
5.  
6.  
7. /// <summary>
8. /// TMP_InputField overload class to fix an Android specific bug.
9. /// [Bug: cannot select a part of the text if m_HideMobileInput = true]
10. /// This class will disappear when the bug will be fixed by Unity in a future update.
11. /// </summary>
12.  
13. public class TMP_TouchInputField : TMP_InputField
14. {
15.     #region Attributes
16.     private FieldInfo m_ShouldActivateNextUpdateInfo;
17.     private MethodInfo activateInputFieldInternalInfo;
18.     private FieldInfo m_SelectionStillActiveInfo;
19.     private FieldInfo m_PreviouslySelectedObjectInfo;
20.     private FieldInfo m_KeyDownStartTimeInfo;
21.     private FieldInfo m_DoubleClickDelayInfo;
22.     private MethodInfo updateMaskRegionsInfo;
23.     private MethodInfo inPlaceEditingInfo;
24.     private MethodInfo isKeyboardUsingEventsInfo;
25.     private MethodInfo assignPositioningIfNeededInfo;
26.     private FieldInfo m_ReleaseSelectionInfo;
27.     private FieldInfo m_WasCanceledInfo;
28.     private MethodInfo updateStringPositionFromKeyboardInfo;
29.     private MethodInfo sendOnValueChangedAndUpdateLabelInfo;
30.     private FieldInfo m_ProcessingEventInfo;
31.     #endregion
32.  
33.     #region Unity methods
34.     protected override void Awake()
35.     {
36.         base.Awake();
37.  
38.         m_ShouldActivateNextUpdateInfo = typeof(TMP_InputField).GetField("m_ShouldActivateNextUpdate", BindingFlags.NonPublic | BindingFlags.Instance);
39.         activateInputFieldInternalInfo = typeof(TMP_InputField).GetMethod("ActivateInputFieldInternal", BindingFlags.NonPublic | BindingFlags.Instance);
40.         m_SelectionStillActiveInfo = typeof(TMP_InputField).GetField("m_SelectionStillActive", BindingFlags.NonPublic | BindingFlags.Instance);
41.         m_PreviouslySelectedObjectInfo = typeof(TMP_InputField).GetField("m_PreviouslySelectedObject", BindingFlags.NonPublic | BindingFlags.Instance);
42.         m_KeyDownStartTimeInfo = typeof(TMP_InputField).GetField("m_KeyDownStartTime", BindingFlags.NonPublic | BindingFlags.Instance);
43.         m_DoubleClickDelayInfo = typeof(TMP_InputField).GetField("m_DoubleClickDelay", BindingFlags.NonPublic | BindingFlags.Instance);
44.         updateMaskRegionsInfo = typeof(TMP_InputField).GetMethod("UpdateMaskRegions", BindingFlags.NonPublic | BindingFlags.Instance);
45.         inPlaceEditingInfo = typeof(TMP_InputField).GetMethod("InPlaceEditing", BindingFlags.NonPublic | BindingFlags.Instance);
46.         isKeyboardUsingEventsInfo = typeof(TMP_InputField).GetMethod("isKeyboardUsingEvents", BindingFlags.NonPublic | BindingFlags.Instance);
47.         assignPositioningIfNeededInfo = typeof(TMP_InputField).GetMethod("AssignPositioningIfNeeded", BindingFlags.NonPublic | BindingFlags.Instance);
48.         m_ReleaseSelectionInfo = typeof(TMP_InputField).GetField("m_ReleaseSelection", BindingFlags.NonPublic | BindingFlags.Instance);
49.         m_WasCanceledInfo = typeof(TMP_InputField).GetField("m_WasCanceled", BindingFlags.NonPublic | BindingFlags.Instance);
50.         updateStringPositionFromKeyboardInfo = typeof(TMP_InputField).GetMethod("UpdateStringPositionFromKeyboard", BindingFlags.NonPublic | BindingFlags.Instance);
51.         sendOnValueChangedAndUpdateLabelInfo = typeof(TMP_InputField).GetMethod("SendOnValueChangedAndUpdateLabel", BindingFlags.NonPublic | BindingFlags.Instance);
52.         m_ProcessingEventInfo = typeof(TMP_InputField).GetField("m_ProcessingEvent", BindingFlags.NonPublic | BindingFlags.Instance);
53.     }
54.  
55.     protected override void LateUpdate()
56.     {
57.         if (!Application.isPlaying || Application.platform != RuntimePlatform.Android)
58.         {
59.             base.LateUpdate();
60.             return;
61.         }
62.  
63.         // Only activate if we are not already activated.
64.         if ((bool)m_ShouldActivateNextUpdateInfo.GetValue(this)) // => if (m_ShouldActivateNextUpdate)
65.         {
66.             if (!isFocused)
67.             {
68.                 activateInputFieldInternalInfo.Invoke(this, null); // => ActivateInputFieldInternal();
69.                 m_ShouldActivateNextUpdateInfo.SetValue(this, false); // => m_ShouldActivateNextUpdate = false;
70.                 return;
71.             }
72.  
73.             // Reset as we are already activated.
74.             m_ShouldActivateNextUpdateInfo.SetValue(this, false); // => m_ShouldActivateNextUpdate = false;
75.         }
76.  
77.         // Handle double click to reset / deselect Input Field when ResetOnActivation is false.
78.         if (!isFocused && (bool)m_SelectionStillActiveInfo.GetValue(this)) // => if (!isFocused && m_SelectionStillActive)
79.         {
80.             GameObject selectedObject = EventSystem.current != null ? EventSystem.current.currentSelectedGameObject : null;
81.  
82.             if (selectedObject == null && m_ResetOnDeActivation)
83.             {
84.                 ReleaseSelection();
85.                 return;
86.             }
87.  
88.             if (selectedObject != null && selectedObject != this.gameObject)
89.             {
90.                 if (selectedObject == (GameObject)m_PreviouslySelectedObjectInfo.GetValue(this)) // => if (selectedObject == m_PreviouslySelectedObject)
91.                     return;
92.  
93.                 m_PreviouslySelectedObjectInfo.SetValue(this, selectedObject); // => m_PreviouslySelectedObject = selectedObject;
94.  
95.                 // Special handling for Vertical Scrollbar
96.                 if (m_VerticalScrollbar && selectedObject == m_VerticalScrollbar.gameObject)
97.                 {
98.                     // Do not release selection
99.                     return;
100.                 }
101.  
102.                 // Release selection for all objects when ResetOnDeActivation is true
103.                 if (m_ResetOnDeActivation)
104.                 {
105.                     ReleaseSelection();
106.                     return;
107.                 }
108.  
109.                 // Release current selection of selected object is another Input Field
110.                 if (selectedObject.GetComponent<TMP_InputField>() != null)
111.                     ReleaseSelection();
112.  
113.                 return;
114.             }
115. #if ENABLE_INPUT_SYSTEM
116.                 Event processingEvent = (Event)m_ProcessingEventInfo.GetValue(this);
117.  
118.                 //if (m_ProcessingEvent != null && m_ProcessingEvent.rawType == EventType.MouseDown && m_ProcessingEvent.button == 0)
119.                 if (processingEvent != null && processingEvent.rawType == EventType.MouseDown && processingEvent.button == 0)
120.                 {
121.                     // Check for Double Click
122.                     bool isDoubleClick = false;
123.                     float timeStamp = Time.unscaledTime;
124.  
125.                     if ((float)m_KeyDownStartTimeInfo.GetValue(this) + (float)m_DoubleClickDelayInfo.GetValue(this) > timeStamp) // => if (m_KeyDownStartTime + m_DoubleClickDelay > timeStamp)
126.                         isDoubleClick = true;
127.  
128.                     m_KeyDownStartTimeInfo.SetValue(this, timeStamp); // => m_KeyDownStartTime = timeStamp;
129.  
130.                     if (isDoubleClick)
131.                     {
132.                         //m_StringPosition = m_StringSelectPosition = 0;
133.                         //m_CaretPosition = m_CaretSelectPosition = 0;
134.                         //m_TextComponent.rectTransform.localPosition = m_DefaultTransformPosition;
135.  
136.                         //if (caretRectTrans != null)
137.                         //    caretRectTrans.localPosition = Vector3.zero;
138.  
139.                         ReleaseSelection();
140.  
141.                         return;
142.                     }
143.                 }
144. #else
145.             if (Input.GetKeyDown(KeyCode.Mouse0))
146.             {
147.                 // Check for Double Click
148.                 bool isDoubleClick = false;
149.                 float timeStamp = Time.unscaledTime;
150.  
151.                 if ((float)m_KeyDownStartTimeInfo.GetValue(this) + (float)m_DoubleClickDelayInfo.GetValue(this) > timeStamp) // => if (m_KeyDownStartTime + m_DoubleClickDelay > timeStamp)
152.                     isDoubleClick = true;
153.  
154.                 m_KeyDownStartTimeInfo.SetValue(this, timeStamp); // => m_KeyDownStartTime = timeStamp;
155.  
156.                 if (isDoubleClick)
157.                 {
158.                     //m_StringPosition = m_StringSelectPosition = 0;
159.                     //m_CaretPosition = m_CaretSelectPosition = 0;
160.                     //m_TextComponent.rectTransform.localPosition = m_DefaultTransformPosition;
161.  
162.                     //if (caretRectTrans != null)
163.                     //    caretRectTrans.localPosition = Vector3.zero;
164.  
165.                     ReleaseSelection();
166.  
167.                     return;
168.                 }
169.             }
170. #endif
171.         }
172.  
173.         updateMaskRegionsInfo.Invoke(this, null); // => UpdateMaskRegions();
174.  
175.         if ((bool)inPlaceEditingInfo.Invoke(this, null) && (bool)isKeyboardUsingEventsInfo.Invoke(this, null) || !isFocused) // => if (InPlaceEditing() && isKeyboardUsingEvents() || !isFocused)
176.         {
177.             return;
178.         }
179.  
180.         assignPositioningIfNeededInfo.Invoke(this, null); // => AssignPositioningIfNeeded();
181.  
182.         if (m_SoftKeyboard == null || m_SoftKeyboard.status != TouchScreenKeyboard.Status.Visible)
183.         {
184.             if (m_SoftKeyboard != null)
185.             {
186.                 if (!readOnly)
187.                     text = m_SoftKeyboard.text;
188.  
189.                 if (m_SoftKeyboard.status == TouchScreenKeyboard.Status.LostFocus)
190.                     SendTouchScreenKeyboardStatusChanged();
191.  
192.                 if (m_SoftKeyboard.status == TouchScreenKeyboard.Status.Canceled)
193.                 {
194.                     m_ReleaseSelectionInfo.SetValue(this, true); // => m_ReleaseSelection = true;
195.                     m_WasCanceledInfo.SetValue(this, true); // => m_WasCanceled = true;
196.                     SendTouchScreenKeyboardStatusChanged();
197.                 }
198.  
199.                 if (m_SoftKeyboard.status == TouchScreenKeyboard.Status.Done)
200.                 {
201.                     m_ReleaseSelectionInfo.SetValue(this, true); // => m_ReleaseSelection = true;
202.                     OnSubmit(null);
203.                     SendTouchScreenKeyboardStatusChanged();
204.                 }
205.             }
206.  
207.             OnDeselect(null);
208.             return;
209.         }
210.  
211.         string val = m_SoftKeyboard.text;
212.  
213.         if (m_Text != val)
214.         {
215.             if (readOnly) // => if (m_ReadOnly)
216.             {
217.                 m_SoftKeyboard.text = m_Text;
218.             }
219.             else
220.             {
221.                 m_Text = "";
222.  
223.                 for (int i = 0; i < val.Length; ++i)
224.                 {
225.                     char c = val[i];
226.  
227.                     if (c == '\r' || c == 3)
228.                         c = '\n';
229.  
230.                     if (onValidateInput != null)
231.                         c = onValidateInput(m_Text, m_Text.Length, c);
232.                     else if (characterValidation != CharacterValidation.None)
233.                         c = Validate(m_Text, m_Text.Length, c);
234.  
235.                     if (lineType == LineType.MultiLineSubmit && c == '\n')
236.                     {
237.                         m_SoftKeyboard.text = m_Text;
238.  
239.                         OnSubmit(null);
240.                         OnDeselect(null);
241.                         return;
242.                     }
243.  
244.                     if (c != 0)
245.                         m_Text += c;
246.                 }
247.  
248.                 if (characterLimit > 0 && m_Text.Length > characterLimit)
249.                     m_Text = m_Text.Substring(0, characterLimit);
250.  
251.                 updateStringPositionFromKeyboardInfo.Invoke(this, null); // => UpdateStringPositionFromKeyboard();
252.  
253.                 // Set keyboard text before updating label, as we might have changed it with validation
254.                 // and update label will take the old value from keyboard if we don't change it here
255.                 if (m_Text != val)
256.                     m_SoftKeyboard.text = m_Text;
257.  
258.                 sendOnValueChangedAndUpdateLabelInfo.Invoke(this, null); // => SendOnValueChangedAndUpdateLabel();
259.             }
260.         }
261.         else if (!shouldHideMobileInput && Application.platform == RuntimePlatform.Android)
262.         {
263.             updateStringPositionFromKeyboardInfo.Invoke(this, null); // => UpdateStringPositionFromKeyboard();
264.         }
265.  
266.         //else if (m_HideMobileInput) // m_Keyboard.canSetSelection
267.         //{
268.         //    int length = stringPositionInternal < stringSelectPositionInternal ? stringSelectPositionInternal - stringPositionInternal : stringPositionInternal - stringSelectPositionInternal;
269.         //    m_SoftKeyboard.selection = new RangeInt(stringPositionInternal < stringSelectPositionInternal ? stringPositionInternal : stringSelectPositionInternal, length);
270.         //}
271.         //else if (!m_HideMobileInput) // m_Keyboard.canGetSelection)
272.         //{
273.         //    UpdateStringPositionFromKeyboard();
274.         //}
275.  
276.         if (m_SoftKeyboard != null && m_SoftKeyboard.status != TouchScreenKeyboard.Status.Visible)
277.         {
278.             if (m_SoftKeyboard.status == TouchScreenKeyboard.Status.Canceled)
279.                 m_WasCanceledInfo.SetValue(this, true); // => m_WasCanceled = true;
280.  
281.             OnDeselect(null);
282.         }
283.     }
284.     #endregion
285. }

 

Bump. There is the same problem with a couple of projects.

 

Ah, this problem has troubled me for a long time, thank you very much for locating the problem.
However, this modification will cause the arrow keys, select-all button, etc. in my phone's IME to not work properly.
It seems that the problem is that functions such as OnDrag() update the selection area, but m_SoftKeyboard.selection is not refreshed synchronously.
So the better solution may be refreshing the selection area of the soft keyboard synchronously(call the code UpdateSelection() below) after OnDragEnd ,OnPointerDown,
MouseDragOutsideRect, and prevent UpdateStringPositionFromKeyboard when dragging(m_UpdateDrag==true)
Too many private functions, it seems to be a better idea to fork out to modify(as attached file)

Code (CSharp):

1.  void UpdateSelection()
2.         {
3.              
4.             int length = stringPositionInternal < stringSelectPositionInternal ? stringSelectPositionInternal - stringPositionInternal : stringPositionInternal - stringSelectPositionInternal;
5.             m_SoftKeyboard.selection = new RangeInt(stringPositionInternal < stringSelectPositionInternal ? stringPositionInternal : stringSelectPositionInternal, length);
6.          
7.         }