fix: position returning to 0

- for calling  refreshUI(media, true) would refresh the view pager position, cause mPos to be set back to 0,
so we retain the original behaviour and call refreshUI(media, false)
- when items have been removed up until the last item in the adapter, the ViewPager's OnPageChangeListener.onPageSelected does not get called for the first item
so mPos is never set to zero and deletion fails.
- we add a call in OnPageChangeListener.onPageScrolled to call onPageSelected(0), when the position == 0 to fix this.

app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/ViewPagerActivity.kt

@@ -1136,7 +1136,7 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
                 val media = mMediaFiles.filter { !mIgnoredPaths.contains(it.path) } as ArrayList<Medium>
                 if (media.isNotEmpty()) {
                     runOnUiThread {
-                        refreshUI(media, true)
+                        refreshUI(media, false)
                     }
                 }
 
@@ -1169,7 +1169,7 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
             val media = mMediaFiles.filter { !mIgnoredPaths.contains(it.path) } as ArrayList<Medium>
             if (media.isNotEmpty()) {
                 runOnUiThread {
-                    refreshUI(media, true)
+                    refreshUI(media, false)
                 }
             }
 
@@ -1413,7 +1413,11 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
     private fun getCurrentPath() = getCurrentMedium()?.path ?: ""
 
-    override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {}
+    override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {
+        if (position == 0) {
+            onPageSelected(0)
+        }
+    }
 
     override fun onPageSelected(position: Int) {
         if (mPos != position) {