InputText: ImGuiInputTextCallbackData::SelectAll() sets CursorPos. Added SetSelection() helper.

Context was for #9174 but not specific to it.

docs/CHANGELOG.txt

@@ -154,6 +154,9 @@ Other Changes:
   - Added ImGuiSliderFlags_ColorMarkers to opt-in adding R/G/B/A color markers
     next to each components, in multi-components functions.
   - Added a way to select a specific marker color.
+- InputText:
+  - ImGuiInputTextCallbackData::SelectAll() also sets CursorPos to SelectionEnd.
+  - Added ImGuiInputTextCallbackData::SetSelection() helper.
 - Text, InputText:
   - Reworked word-wrapping logic:
     - Try to not wrap in the middle of contiguous punctuations. (#8139, #8439, #9094)

imgui.h

@@ -2650,9 +2650,10 @@ struct ImGuiInputTextCallbackData
     IMGUI_API ImGuiInputTextCallbackData();
     IMGUI_API void      DeleteChars(int pos, int bytes_count);
     IMGUI_API void      InsertChars(int pos, const char* text, const char* text_end = NULL);
-    void                SelectAll()             { SelectionStart = 0; SelectionEnd = BufTextLen; }
-    void                ClearSelection()        { SelectionStart = SelectionEnd = BufTextLen; }
-    bool                HasSelection() const    { return SelectionStart != SelectionEnd; }
+    void                SelectAll()                 { SelectionStart = 0; CursorPos = SelectionEnd = BufTextLen; }
+    void                SetSelection(int s, int e)  { IM_ASSERT(s >= 0 && s <= BufTextLen); IM_ASSERT(e >= 0 && e <= BufTextLen); SelectionStart = s; CursorPos = SelectionEnd = e; }
+    void                ClearSelection()            { SelectionStart = SelectionEnd = BufTextLen; }
+    bool                HasSelection() const        { return SelectionStart != SelectionEnd; }
 };
 
 // Resizing callback data to apply custom constraint. As enabled by SetNextWindowSizeConstraints(). Callback is called during the next Begin().