impr: Jump to top of selection instead of the bottom

Fixes #2354

Author: WerWolv

plugins/ui/include/ui/hex_editor.hpp

@@ -55,6 +55,9 @@ namespace hex::ui {
         }
 
         ScrollPosition& operator=(ImS64 value) {
+            if (value < 0)
+                 value = 0;
+
             this->get() = value;
             return *this;
         }
@@ -157,7 +160,7 @@ namespace hex::ui {
 
             m_selectionStart = std::clamp<u64>(start, 0, maxAddress);
             m_selectionEnd = std::clamp<u64>(end, 0, maxAddress);
-            m_cursorPosition = m_selectionEnd;
+            m_cursorPosition = m_selectionStart;
 
             if (m_selectionChanged) {
                 auto selection = this->getSelection();

plugins/ui/source/ui/hex_editor.cpp

@@ -1054,15 +1054,15 @@ namespace hex::ui {
 
                         // Calculate the current top and bottom row numbers of the viewport
                         ImS64 currentTopRow = m_scrollPosition;
-                        ImS64 currentBottomRow = m_scrollPosition + m_visibleRowCount - 3;
+                        ImS64 currentBottomRow = std::max<ImS64>(m_scrollPosition + m_visibleRowCount - 3, 0);
 
                         // Check if the targetRowNumber is outside the current visible range
                         if (ImS64(targetRowNumber) < currentTopRow) {
                             // If target is above the current view, scroll just enough to bring it into view at the top
-                            m_scrollPosition = targetRowNumber - (m_visibleRowCount * m_jumpPivot);
+                            m_scrollPosition = targetRowNumber + m_visibleRowCount * m_jumpPivot - 3;
                         } else if (ImS64(targetRowNumber) > currentBottomRow) {
                             // If target is below the current view, scroll just enough to bring it into view at the bottom
-                            m_scrollPosition = targetRowNumber - (m_visibleRowCount - 3);
+                            m_scrollPosition = targetRowNumber - 3;
                         }
 
                         m_jumpPivot = 0.0F;